Marine Corps Vietnam Tankers Historical Foundation®

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The M50a1 Ontos

The Ontos Anti-Tank Vehicle.

©2001 Peter Brush

By any measure, the Ontos was one of the most interesting “things” to come down the road of United States military armored development. The idea for this vehicle was born in the aftermath of World War II when the U.S. Army perceived the need for a new reconnaissance vehicle. Then it evolved into a tank destroyer for use with the Army on the nuclear battlefields of Europe. Next it was deployed in Marine Corps anti-tank (AT) battalions. The Ontos most significant contribution was in the Vietnam War, but in a role much different from the role for which it was designed. This is the story of the Ontos, officially the “Rifle, Multiple 106mm, Self-Propelled, M50.”

The adaption of the internal combustion engine to warfare brought about the removal of the horse from the battlefield. The reconnaissance mission formerly performed by cavalry remained. By the end of World War II, the motorcycle, jeep, armored car, and light tank all tried to fill the gap, all without complete success. A classified 1953 U.S. Army report noted:

There is an urgent and immediate need in our army for a vehicle similar in performance to the jeep, but at the same time affording some armored protection and greater cross-country mobility, for use by reconnaissance personnel, commanders, messengers, and liaison officers who are frequently exposed to small arms fire.”

At that time jeeps and half-tracks were authorized in the command, scout, and support elements of the Army reconnaissance platoon. The Ontos was considered as a replacement. After considerable study the Army concluded that although the vehicle had outstanding cross-country mobility and armor protection, it had deficiencies in the areas of storage space, lack of speed, lack of range, and excess weight. Ironically, given the vulnerability of the M50 to enemy mines in Vietnam, the Army concluded these test vehicles “offered protection against atomic bombing.” The Army decided to stick with its M38A1 ¼ ton trucks and M21 mortar carriers for reconnaissance platoon use. Spurred by Secretary Frank Pace, Jr., the Army was developing the Ontos as a family of vehicles, to include infantry carrier, antitank antiaircraft, self propelled artillery and logistics carrier.

During World War II, the Army embraced the tank destroyer concept, which called for the placement of large-caliber anti-tank guns on lightly armored carriages. These could quickly be moved to any area under enemy tank threat. This concept was never embraced by the Marine Corps to any extent. The tank remained the favored anti-tank weapon for the Marines in the immediate postwar period. In addition to duties as naval infantry, postwar planners envisioned a role for the Corps in any European conflict

between the United States and the Soviet Union. Late 1940s war planning put the Marines into direct conflict with front-line units of the Red Army. In the Pacific War the Marines dealt with sporadic attacks by small Japanese tanks. In the future war Marine tankers would have to face a highly mechanized Soviet force equipped with large numbers of medium and heavy tanks.

Using tanks to destroy enemy tanks proved less than satisfactory in the Korean War: too often the weight of American medium tanks rendered them too road bound. Marine planners, cognizant of the formidable threat posed by Communist armor, returned to the World War II tank destroyer concept. In 1949 the USMC Armor Policy Board specifically noted “There is a requirement for a destroyer-type tank to destroy hostile heavily armored vehicles….”

As early as 1944, Army production and logistics considerations began to determine Marine Corps tank decisions. Although some of the USMC armor requirement was developed and produced by the Navy’s Bureau of Ships (e.g., amphibious tractor or amtracs), the Corps came to fully depend on the Army for its tank procurement. In 1951, based on an Army initiative, Allis Chalmers became the lead contractor for this new anti-tank vehicle. It would be built at the company’s La Porte, IN, factory.

In 1953, Michigan Congressman Gerald R Ford held congressional hearing for Army appropriations. When discussion turned to anti-tank capabilities, the testimony of Army generals was taken off the record and not included in the printed transcript. The public became aware of Ontos development only by mistake. According to a report in the New York Times dated June 26, 1953, the congressional testimony was classified “Secret”. The newspaper noted “An entirely new weapons-carrying vehicle, nicknamed ‘The Thing’ but carrying the official designation Ontos, to be used variously, including as a mount for a new ‘highly-powered’ recoilless rifle and for a quadruple .50 calibre antiaircraft weapon against low flying planes.’ Army officials expressed amazement and appeared appalled when copies of the 1,667-page printed testimony released by the subcommittee reached the Pentagon.

The first production model of the M-50 came off the assembly line on 31 October 1956. The original Ontos emphasized firepower over crew comfort. The hull was derived from the T55/T56 series of tracked armored personnel carriers. It was powered by a six cylinder in-line gasoline engine, the General Motors SL 12340, which developed 145 horsepower at 3,400 rpm (this was later upgraded to a Chrysler V-8). This power source was coupled to a XT-90-2 transmission, which drove the front sprockets, which turned the tracks. Maximum road speed was 30 mph on improved roads. The Ontos had terrain navigation ability superior to tanks. Range was 190 miles on primary roads, 120 miles on secondary roads, and 50 miles cross country with a 47 gallon internal fuel tank. With fording kit installed the vehicle could cross streams as deep as 60 inches. The vehicle weighed nine tons. It had a three man crew: driver, loader, and gunner. For a tracked vehicle it made little noise. Consequently, there was no intercom between the gunner and driver, although there was a loudspeaker on the radio. The M-50 was not portable by an available helicopter although it could be air transported by R4Q aircraft. Two Ontos could be landed over the beach in a LCM-6 (Landing Craft, Mechanized). The M-50 could climb a 60 percent grade climb over a 30-inch obstacle. The engine would run wet, and the vehicle could ford two feet of water in normal configuration. With fording equipment it could go deeper.

The main weapon consisted of six 106mm M40A1C recoilless rifles mounted on a central turret. The guns extended beyond the hull on both sides. Built with simplicity in mind, this rifle was the same weapon used by infantry on a fixed mount. These guns could be fired individually, in pairs, or all at once. Fifty caliber spotting rifles were mounted on four of the recoilless rifles. Two of the recoilless rifles were equipped with a spotting rifle and sight and could be removed from the vehicle for use on ground mounts (these spotting rifles could not be fired from inside). The sights and could be removed from the vehicle for use on ground mounts. The Ontos also had a .30 caliber machine gun. Each vehicle carried a normal load of 18 rounds of 106mm ammunition (six in the rifles plus a dozen more in the ammo bin). These weapons were externally and coaxially mounted and were fired electrically. The rate of fire was four aimed rounds per minute with all guns loaded and fired individually.

The trajectories of the spotting rounds and the 106mm rounds were very similar to a distance of 1,100 yards. Beyond 1,100 yards the trajectories differed, causing the effectiveness of this spotting system to decrease as range increased. The spotting rifle could not be used beyond 1,500 yards, necessitating the use of burst-on- target and bracket techniques of fire adjustment at these greater ranges. High Explosive Anti-Tank (HEAT) ammunition for the 106mm rifle would penetrate the armor of any known tank (16” of armor at 0 degrees obliquity). The Ontos’ armor was one-half inch plate except for the floor, which was only 3/16” inch thick. The upper sloped armor would withstand all small arms fire, but was vulnerable to .50 caliber armor piercing rounds. Artillery airbursts could cause severe damage to the Ontos’ guns and external fire control equipment.

Frank Pace, Secretary of the Army during the Truman administration, initially supported the M50 for Army use. Pace noted, “If Ontos is there, tanks had better get the hell off the battlefield.” Not everyone agreed with Pace. Others felt it was too lightly armored, underpowered, and incapable of sustained combat. The Marine Corps accepted the Ontos after the Army rejected it. The Marines did not have the specialized supply and maintenance capabilities of the Army, and the Ontos was a simple vehicle. It had fewer parts than other armored vehicles. There was no heavy turret. The engine was a common truck engine found on various military and civilian vehicles. The fire control system was simple: according to LtCol. E.L. Bale, Jr., a Marine instructor at the Army Armor School, the average Marine could master the system “as easily as he has the pinball machine in the local drug store.” The Corps ordered 13 million dollars worth, about 300 vehicles. Production was to run for about one year.

The Ontos, manned by infantrymen, was quickly integrated into regimental anti-tank companies. These companies contained 12 Ontos, five officers, And 91 enlisted men. Each unit consisted of three Ontos platoons of four vehicles each. The unit’s 72 anti-tank rifles could be fired from the vehicle or dismounted and fired from ground mounts. Its first non-training deployment abroad came in July 1958. The Lebanon Crisis saw Marine Battalion Landing Teams (BLT) of the Navy’s Sixth Fleet come ashore to stabilize the weak Lebanese national government. This 2nd Provisional Marine Force included 15 M48 tanks, 10 Ontos, and 31 LVTP5 amtracks (Landing Vehicle, Tracked). These vehicles provided general Force security and protection for armored patrols until a larger Army tank force could be sent from Germany. The Marines began reembarkation in mid-August.

The Ontos next saw action in 1965 in the Caribbean. In April the Dominican Republic was sliding into civil war as reformers did battle with right-wing military forces. The 6th Marine Expeditionary Unit, the Caribbean quick-reaction force, was ordered to ashore in order to evacuate civilians and reinforce security at the American embassy. A company each of tanks and amtracs (LVTs) plus two platoons of Ontos were part of the landing team, which took the side of the Dominican military.

Ontos were organized in the Marine Division into Anti-Tank Battalions. Each battalion was composed of one headquarters and service company plus three anti-tank companies. Each of these letter companies contained three platoons of five Ontos for a total of 45 Ontos vehicles per battalion. Planned distribution in the Marine Division was for a company of 15 Ontos (three platoons) for each of the division’s three infantry regiments. Ontos companies, along with tanks and amtracs, landed with the 9th Marine Expeditionary Brigade at Da Nang, Vietnam, in the first half of 1965. Within one year, both the 1st and 3rd Anti-Tank Battalions were ashore in Vietnam. Unlike the enemy in the Korean War, the Vietnamese Communist military forces possessed significant anti-armor capabilities in the form of recoilless rifles and rock propelled grenades. The Ontos’ thin floor armor (3/16”) made it especially vulnerable to mines. Consequently, and as opposed to its designed role, Ontos spent a great portion of their time in static defense positions.

Initially Ontos units were deployed in defense of the Da Nang airfield. In August, 1965, the Marines began Operation Starlite, the first big battle of the war. At 0730 on August 17, tanks and Ontos rolled off amphibious landing craft (LCUs and LCMs) and made their way ashore south of Chu Lai in support of the assault companies. Later in the day a Marine armored column was halted when a M-48 tank was hit with recoilless rifle fire. The Viet Cong (VC) poured mortar and small arms fire into the Marine positions, quickly killing five and wounding 17. The Ontos maneuvered to provide frontal fire and flank protection until enemy fire let up. The following month, in Operation Golden Fleece, a combined infantry-armor assault force including Ontos attacked a VC main force unit trying to collect a rice tax in a Vietnamese village near Da Nang. The enemy was forced to break contact and flee the area.

After establishing themselves at Da Nang and Chu Lai, the Marines built their third base at Phu Bai, in Thua Thien Province 35 miles northwest of Da Nang. Initially, defense of Phu Bai was provided by the 2nd Battalion, 1st Marines (Reinforced) which had a platoon of M50s attached. It was not only the Marines who were expanding their forces in the northern part of South Vietnam: both the VC and North Vietnamese Army (NVA) also increased their forces, and both sides sustained heavy casualties. In late June, on Operation Jay, a large, heavily armed VC force ambushed a South Vietnamese Marine Corps convoy moving north on Route 1, the main north-south highway in Vietnam. At 0830 hours on June 29, the attacking force struck the convoy with mortar and recoilless rifle fire, quickly hitting ten trucks. U.S. Marines quickly sent reinforcements, including Ontos, to assist the SVN Marines. The VC force lost interest and tried to break contact. While crossing open ground, the M50 platoon opened fire and “obliterated a VC squad on a ridgeline with a single 106mm salvo.” A M50 platoon commander even captured an enemy soldier. Over 185 enemy soldiers were killed in this action.

Marines and their armor were deployed in I Corps, the northernmost of four military districts in Vietnam. An exception to this was Special Landing Force (SLF) of the Navy’s Seventh Fleet, the strategic reserve for the Pacific Far East. The SLF was available for amphibious landings in South Vietnam. Gen. William Westmoreland, commander of U.S. forces in Vietnam, decided to use the SLF to clear Viet Cong forces from the Rung Sat Special Zone south of Saigon. VC gunners were firing on ships using the river channel that supplied the Vietnamese capital. The result was Operation Jackstay, March 26-April 6, 1966. The operation had limited success but not due to lack of ingenuity of the Marines, who experimented with riverine warfare techniques including mounting an Ontos on a LCM to provide fire support. Only 63 enemy troops were killed; however, the shipping channel was at least temporarily clear.

The following incident illustrates the vulnerability of the M50 to enemy mines. It was spring, 1966. An armored column supporting Company “K”, 3/9 was returning to base camp near Da Nang. Three tanks and an Ontos went over a stream at a place called Viem Dong Crossing without mishap. As the second M50 crossed, Platoon Commander Lt Allen Hoof heard a “pop”, turned rearward, and saw the upper half of the vehicle blown off the lower half, and lying upside down next to it. All three crewmen were wounded. Acting Ontos Commander PFC Greg Weaver was quickly removed from the vehicle but died almost immediately. The mine explosion, perhaps either command detonated or activated by a counter, caused the detonation of a 106mm round stored directly under the commander. This secondary explosion blew the turret off the vehicle and killed Weaver.

Since enemy tanks were not a problem for Marines in Vietnam, Ontos use reverted to its secondary mission: providing direct fire support for infantry. By late 1966 problems with Ontos became evident. The supply of tracks was depleted, which caused breakdowns on operations. This caused a reluctance to utilize the M50. An even more important reason was several incidents of accidental firings of recoilless rifles which cost some Marine lives. This was an extremely serious problem for Ontos on convoy duty. These accidents were caused by overly tight adjustment of the firing cable allowing the firing pin to release prematurely. This adjustment was a crew responsibility and required thorough understanding of the firing cable, sear, and trigger. These mishaps caused restrictions to be placed on Ontos’ use.

By 1967 the Marines were fighting two wars in Vietnam. The 1st Marine Division engaged in counter guerrilla operations in the southern part of I Corps while the 3rd Marine Division conducted mostly conventional war against NVA along the Demilitarized Zone (DMZ) in the north. As the Marines moved northward to counter the NVA threat, Ontos and tanks provided important support. In May 1967, the 2nd Battalion, 9th Marines (2/9) and 2nd Battalion, 26th Marines (2/26) began Operation Hickory north of Con Thien. Fighting against enemy forces in well prepared bunkers and trenches was heavy. M50s, using the proper ammunition, proved to be devastating antipersonnel weapons. After the conclusion of Hickory, 2/9, accompanied by tanks and Ontos, was sent on a spoiling attack into the DMZ. On this operation the tracked vehicles proved more of a liability than a tactical asset as the terrain restricted them to the road. Instead of providing infantry support, the M50s and tanks required infantry protection against NVA rocket propelled grenade (RPG) attack. Using these vehicles as ambulances to evacuate the wounded further reduced their offensive capabilities.

1967 saw the introduction of CH-53 Sea Stallion heavy-lift helicopters for the Marines in Vietnam. The first models had a six-ton external lift capability. This meant an Ontos could be transported by helicopter if it was broken down into components with the hull transported externally. It could then be reassembled and operated at destination, giving it a transportability beyond its design considerations. M50s could also go where tanks feared to tread (or should have): in a 1966 operation, tanks got stuck in flooded rice paddies. Ontos, with less ground pressure, were able to drag timbers up to the tanks without bogging down. In Operation Jay, mentioned above, the Ontos of B Company, 3rd Anti-Tanks were able to assist the SVN Marines because they could cross a pontoon bridge - - the only tracked vehicles light enough to drive to the operation. Ontos could go more places than many people thought possible.

In December 1967, the 1st and 3rd Anti-Tank Battalions were de-commissioned in Vietnam. One company from each battalion was attached to the tank battalions. 1968 saw Ontos assume an important role in some of the heaviest fighting of the entire war, the Battle of Hue during the Tet Offensive. In February, 14 NVA battalions seized control of most of the city. The Americans and South Vietnamese faced the formidable task of retaking this important cultural center of the nation. The result was urban fighting unlike anything seen in the war. The attacking Marines had to take each building and each block one at a time. This close-quarter combat and low flying clouds, coupled with the desire to minimize damage to the city itself, meant there could be little reliance on artillery and close air support.

Four tanks from the 3rd Tank Battalion along with a platoon of Ontos from the Anti-Tank Company, 1st Tank Battalion, joined the advance against strong enemy resistance. LtCol Ernest Cheatham, commander of 2/5, had reservations about using tanks. One tank sustained over 120 hits and another went through five or six crews. Infantry commanders liked the Ontos better. Cheatham described the M50 “as big a help as any item of gear we had that was not organic” to the battalion. Regimental commander Col. Stanley Hughes went even further when he claimed the Ontos was the most effective of all the supporting arms the Marines had at their disposal. Its mobility made up for its lack of armor protection, noting that at ranges of 300 to 500 yards, its recoilless rifles routinely opened “4 square meter holes or completely knock[ed] out an exterior wall.” The armor plating of the M50 was sufficient protection against enemy small arms fire and grenades. However, B-40 ant-tank rockets were another story: an Ontos with 1/1 was knocked out and the driver killed on February 7 while supporting the 1st Battalion, 1st Marines. The essential role of tanks and M50s in the fighting illustrated by the fact that Marines had to hold up their advance from time to time for lack of 90mm tank and 106mm Ontos ammunition.

The Perfume River flows through Hue. After clearing the south bank on February 11, the 1st Battalion, 5th Marines pushed north to clear NVA forces firmly entrenched in the 4-square-mile Citadel, location of the former Imperial Palace. USMC M-48 tanks and Ontos were placed under the command of the attached tank platoon commander. Tactically, the tank or Ontos commander, working with the infantry commander, would reconnoiter a particular target area, usually a masonry structure blocking the Marine advance. Returning to their vehicle, the tank or Ontos commander would move forward at full speed while the infantry laid down a heavy volume of fire. Upon reaching a position where fire could be directed on the target, the vehicle commander halted the vehicle, fired two or three rounds into the structure, then quickly reversed direction and returned to friendly front lines. Casualties among armor crews were high. On February 24, South Vietnamese troops finally dislodged NVA forces from the Citadel. By the time the battle for Hue was over, 50 percent of the city was destroyed.

Before, during, and after the Battle of Hue, the 26th Marine Regiment was fighting the North Vietnamese at Khe Sanh. Here the enemy tank threat was real: 17 days into the battle at Khe Sanh, NVA tanks helped overrun the nearby Special Forces camp at Lang Vei. Ten M50s from B Co (-) 3rd Anti-Tank Battalion were incorporated into Khe Sanh’s defenses. They were sometimes used for reconnaissance but more often in static perimeter defense roles. Author Robert Pisor notes the Ontos at Khe Sanh had “enough flechette [anti-personnel] ammunition to pin the entire North Vietnamese Army to the face of Co Roc Mountain.”

The Marine Corps began to deploy its forces out of Vietnam in 1969. Tank and amtrac units rotated early as fighting had ebbed in the Corps’ area of responsibility. By this time the M50 parts supply was depleted and the 106mm rifle was about to be replaced by other weapons. M50 mechanics cannibalized disabled machines to keep others running, but after Hue the Ontos were worn out. Ironically, excess Ontos were given to Army forces (recall that the Army initially rejected the Ontos as being unsuitable for its requirements). These Army Ontos went to Company D, 16th Armor, 173rd Airborne Brigade. The Army used its Ontos until they ran out of spare parts, then employed them in fixed bunkers. In the United States, the Marine 2nd Anti-Tank Battalion was disbanded along with the 5th Marine Division. The last Ontos garrison was stationed at Guantanamo Bay, Cuba. It continued to operate until 1980 by which time it had one operation vehicle. Two others were used for parts.

Upon return to the United States, the tops of the vehicles were removed. Many of the chassis were sold for use as construction equipment or give to local governments for rescue work. One “platoon” of surplus M50s wound up in the service of the North Carolina Forestry Service for use as fire fighting vehicles. According to Vietnam veteran and former Marine Mike Scudder, Ontos today are scarce. In fact, there are more surviving World War I tanks than Ontos. Scudder should know: he bought the seven from North Carolina and is restoring two of them. More than 60 Ontos are believed to be stored in the desert at the Marine Corps facility, Naval Air Warfare Center, China Lake, CA.

Was the Ontos a successful addition to the Marine Corps arsenal? The answer is quite simply, yes and no. The primary mission of the M50 was a tank destroyer. In the actual tactical environments in which it was deployed, there was little use for this ability.

Its secondary mission was the provision of direct fire support for the infantry. In this role the Ontos was underutilized. The reason, according to Major D.C. Satcher writing in the Marine Corps Gazette, is because, unlike artillery, air, and tanks, Ontos were little emphasized in Marine officer training. Ontos were never used in any tactics problems in The Basic School. Ontos crew did not have their own MOS (instead, they were infantry MOS). An Ontos officer normally served one tour with an M50 unit, then moved on. A weapons system that is under-emphasized will be underutilized.

Although quick and agile (the M50 could go places no other Marine armored vehicle could go), it had limitations. In addition to the problems previously noted (premature firing and vulnerability to mining), the recoilless rifles had to be loaded externally which meant the crew had to leave the protection of an armored hull in order to reload. The 106mm recoilless rifle is no stealth weapon: when fired, the tremendous back blast makes the Ontos’ location visible to the enemy. Ontos crew had to ensure no friendly troops were in the large back blast area when operating in confined areas.

There was no enemy armor for the Ontos to destroy in Vietnam. Still, Marines are famous for their ability to improvise, and the enemy infantry were plentiful. The M50 was a formidable anti-personnel weapon. A couple of Ontos on the perimeter could decimate Communist forces attack on Marine fixed positions, a static role quite the opposite of its designed high-mobility anti-armor role. My favorite example of Marines ability to adapt to local tactical conditions is the main streets of Hue City in February 1968. Not only good at destroying structures, Ontos were able to provide a “smoke screen” for infantry attacks: when Marine artillery was unable to provide white phosphorus rounds, Ontos could fire “beehive” rounds (explosive shells filled with thousands of small darts) fired into masonry structures, thereby creating a dust cloud that screened infantry movement. Marine infantry loved their Ontos. In Phase Line Green: The Battle for Hue, 1968, author Nicholas Warr describes how the M50 platoon pounded the enemy positions, accompanied to the choruses of “Get some!” sung by infantry holed up in houses, waiting to move forward. Fact is, even with its limitations, the Ontos was used and, to a considerable degree, used up in Vietnam, providing invaluable support for the Marines in I Corps.

Peter Brush

For additional reading:

Kenneth W. Estes, Marines under Armor (Annapolis, MD: Naval Institute Press, 2000)

William B Allmon, “The Ontos,” Vietnam, August 1994

Note: This article is the revision of an earlier article published in Vietnam magazine, October, 2002. It includes corrections to the original article and additional information.

About the Author: Here's how he first learned of Ontos. When he was a tadpole, his father was stationed at the Marine Corps Supply Depot at Barstow, California. This was in the 1950s. He saw plenty of tanks and amtracs in their huge storage areas but the Ontos was especially interesting looking; so different and formidable, compared to anything else, even though much smaller.

He saw them again next time at Khe Sanh during the siege. Often they were deployed at night facing down the long axis of the airstrip, in case the NVA decided to attack the base from that direction -- as he recalls, the airstrip extended right to the perimeter, even a bit beyond.  After a few weeks of fighting, his thinking was, "come on in, NVA, and see what Ontos with beehive rounds can do!"

Ah, and the rest is history

And more: Peter served in the Marine artillery units in Quang Tri province from August 1967 to July 1968 with 1st Battalion, 12th Marines and 1st Battalion, 13th Marines. With 1/13 he was admin chief of Mortar Battery at Khe Sanh during the 1968 siege. He has a BA and MA in history and a MLIS degree in library science. He retired from Vanderbilt University in 2013, where he was the history librarian. He has published over 100 articles, mostly about the Marines in Vietnam. (Many of which are found on the Foundation’s web site)


Ugly ONTOS is Underrated

Maj. D.C. Satcher

Marine Corps Gazette (pre-1994); Nov 1969; 53, 11; ProQuest Direct Complete Pg 88

Without doubt the strangest looking combat vehicle in the Marine Corps in the ONTOS. It has been scoffed at, ignored and underrated for many years. But this strange looking weapon has potentials that many of us have overlooked. Its primary mission is, of course, to defeat enemy armor. The secondary mission, to provide direct fire support for the infantry, is the subject of this article. This can be accomplished by answering the following questions with a view towards its past use in Vietnam. Why isn’t it used? What are its positive and negative features? How can it be used in its secondary mission?

Why isn’t it used? The foremost reason is that it is not thought of. Artillery, air, and to a lesser extent tanks immediately come to mind anytime something larger than a rifle is needed. It is second nature to call on them. They have all been in our arsenal for many years and are stressed in our teachings. The ONTOS, though, has not been around very long and is not stressed in our teachings.

The ideas and principles we learn at The Basic School stay with us for many years and guide our later actions. At The Basic School, artillery, air and tanks are the supporting arms which receive the most emphasis. The ONTOS makes only two appearances during a Lieutenant’s 21-week course. The first is at a field firing of the 106mm recoilless rifle. The ONTOS does fire, but the emphasis is not placed on a vehicle which can traverse rough terrain and deliver accurate fire on a target within seconds after the need arises; rather the emphasis is placed on another means of transporting the 106. The next appearance occurs at a static display of Marine Corps tracked vehicles. It is never used in any tactics problem, thereby taking an inferior position to the other supporting arms.

Every major supporting arm in the Marine Corps is represented by a particular MOS. Officers stay in the MOS for years and constantly “sell” their weapon. The ONTOS cannot boast of its own officer MOS. The primary MOSs in an Antitank Battalion are 0302 and 1802, infantry and tanks. When an officer is assigned to an Antitank Battalion, it is usually for only one tour and then he moves on. He is not there long enough to develop the complete understanding that is necessary. Thus the knowledge, enthusiasm and attachment are usually missing to aggressively “sell” the ONTOS, particularly in RVN.

The ONTOS started its decline in RVN in late 1966. Two factors were involved. They supply of track was depleted, causing breakdowns on operations and a reluctance to employ it. The primary reason, though, was that several accidental occurred which cost some Marine lives. This caused the doubt that was cast on the ONTOS. These accidents were caused by the firing cable, sear and trigger working improperly either separately or together. If the firing cable were adjusted too tightly, the firing pin could release. This adjustment was a crew responsibility and required thorough understanding. Such a design, peculiar to the ONTOS, was not good. How many weapons do we have that require such an adjustment by the crewmen or individual? These accidental firings caused restrictions to be placed on the vehicle and a further decline in its use. The longer the vehicle stayed in RVN, the less it was used, up to the day the last one was removed in Okinawa.

What are its positive and negative features? It can save Marine lives. How many times have infantry elements encountered automatic weapons, bunkers or some obstacle where a well placed 106mm round could do the job? The ONTOS’s fire is accurate to 1200 meters and it cannot miss at 100 or 200 meters. Each vehicle carries eighteen 106mm rounds, or ninety per platoon, and a machine gun. The infantry does not have to worry about communicating with the ONTOS, for each vehicle has the radios necessary to monitor the infantry net as well as its own. The distance it can drive on a tank of gas is farther than the infantry can walk in days, making the resupply problem less burdensome than expected.

Trafficability is usually looked at as the major limitation of any tracked vehicle. First, let us see where it can go. It can drive from Da Nang to Dong Ha and down Route #9, negotiating any bridge on the way. Any bridge that can hold ten tons can support the ONTOS. It has gone through many flooded rice paddies, for the ground pressure is not that great. During one operation in the Khobi Tahn Tahn area in 1966, tanks got stuck due to heavy rains. ONTOS were used to drag timbers up to the tanks and did not get stuck in the process. ONTOS have even been lifted by helicopters on several occasions. One load consisted of the six recoilless rifles, ammunition and associated equipment. The hull was then lifted externally by a CH-53 helicopter. This has been done on several occasions in the Da Nang area. The ONTOS were lifted to an area, assembled and operated. Granted, trafficability is the big limitation, but the ONTOS can go more placed than most people believe possible. Breakdowns are another limitation, but like anything mechanical, an adequate supply of repair parts will keep this to a minimum.

How can the ONTOS be used in its secondary mission? The ONTOS is not a tank and should not be used as one. It should be used to follow the lead infantry elements on sweeps where terrain is negotiable. When an obstacle is encountered, such as an automatic weapon, it can be brought forward and take the target under fire. The vehicle has light armor protection, thus it takes a .50 caliber or larger weapon to knock it out. Definitely, the ONTOS cannot go on every operation, but there are innumerable places that the vehicle can negotiate, and be an asset to the fire power of the infantry.

An excellent example of its usefulness was on June 29, 1966. “B” Company, 3rd Antitank Battalion was on Operation JAY north of Hue with the 4th Marines. Approximately 1,400 meters away on Route #1, a Vietnamese Marine Corps convoy was ambushed. The ONTOS Company and “I” Company 3rd Battalion, 4th Marines went to their aid. The ONTOS crossed a pontoon bridge across the Song O Lau, which “I” Company stayed to protect, and went to the ambush. As soon as the ONTOS appeared at the ambush site all NVA firing stopped. The vehicles swept through the short brush west of Route #1 engaging many NVA. Several of the enemy were killed and one captured by an ONTOS platoon commander. ONTOS were used because there was a need for a tracked vehicle with heavy fire power and they were the only ones available. Why? Because they were the only tracked vehicles light enough to drive to the operation.

The ONTOS can be very useful if we can be motivated to think about its capabilities and utilize its potential. Many people have a residual attitude that the vehicle is no good. True, the rifles need a modification and repair parts are needed; but other than that, the ONTOS is a good weapon as it is. It is an important part of our combat power that is being overlooked. Therefore, once the needed improvements have been made, we should put it to good, aggressive use in RVN and elsewhere, even if it is strange looking.


Improving” the Ontos

A number of ideas to “improve” the Ontos to better its capability to support the infantry units in both their defensive and offensive missions were experimented with. Here is evidence from the March 1966 1st Anti-tank Battalion’s Command Chronology that merited consideration. The testing of the idea took place on Okinawa by 1st AT’s, based on feedback from in-country AT and Infantry units. It appears (i.e., reference to ordering 60 M85 .50 caliber machine guns) that this was a done deal. (?)

The above picture is a cut/paste from the referenced Command Chronology

Below is a snap shot of the “finished product”.

Let’s Transfer Ontos to Barstow

Bernard E Trainor

Copy of “Let’s Transfer Ontos to Barstow” Marine Corps Gazette May 1961

Ontology may be described as the science of reality, the investigation of the essential properties of a thing. What, pray tell, does this philosophical noun have to do with the profession of arms? With apologies to Plato and the gang, we will take the disciplines of ontology and apply them to the existing "thing" which has bastardized its name - Ontos. If consigned to the limbo of Barstow tomorrow, Ontos will have shared the distinction (with cotton khaki battle jacket) of being one of our Corp's more short-lived expressions of individuality. It is doubtful that the plaintive wails which attended the honorable retirement of the "60 mortar" would ever echo around the driver's hatch of the tracked "Dempster Dumpster." Rightly so, for weighing about the same as a healthy pachyderm, Ontos is a white elephant in our family of versatile weapons. This air-transportable orphan was adopted with sincerity by the Corps, during a period of helicopter intoxication, to replace the AT function of the tank within the division. It was adopted to provide the division with a realistic anti-tank weapon. This it fails to do. A weapon, to be worthwhile, should give us the maximum return in terms of its effectiveness for a minimum investment. I maintain that in this regard, Ontos is hardly blue chip stock. Six shares of BAT* stock give us a greater return on our money than one share of Ontos common. Even then, however, we have a weak investment portfolio.

Let's look at the primary mission of Ontos, its anti-tank task. We must concede that Ontos can knock out tanks. Anybody's. If you have ever watched a trained crew operate you know what I mean. However, go beyond the guns and look at the weapon as a whole. Armor protection is insignificant; therefore, it cannot stand a slugging match. You may say, "Weaponry is ascendant over armor and not even the heaviest tank can withstand a direct hit from a modern AT gun." I maintain that Ontos can't even slug it out with a grease gun. One blast of automatic fire at the unprotected banks of guns will sever the exposed fire control system; leave the hull intact and us with $70,000 liability. At least with BAT*s it would take six bursts in six different directions to accomplish the same end. Shall we move on?

Back-blast not only gives the nearby infantry a cracking good fright but tends to incinerate the unschooled to its rear. Admittedly, this is hardly a consideration in battle, but, more importantly, that impressive blast also tips your location to the enemy's base of fire (tank & SP). Needless to say, Ontos as a source of annoyance will be honored by immediate and unfriendly attention. Of course, here is where Ontos maneuverability comes into play and hasty withdrawal to defilade saves the day. But does it? Hardly. We have to delay and raise the travel locks to support the guns before we can move, else we will snap our multiple muskets into an attitude of decided embarrassment-pointing at mother earth. However, to raise these travel locks, the gunner must center the guns in azimuth and elevation while the driver must crank an archaic hydraulic system for an eternity until the locks marry with the tubes and allow safe movement. Reflect if you will, the action of that enemy base of fire during all this. Assuming that we are successful in eventually getting into defilade, where do we go from here? An alternate position would be logical, but remember that T-54 in the distance is wise to us now and his 100mm is looking in our direction. If we reappear nearby - whacko! Okay, insure that the alternate position is not in the immediate vicinity of the primary position. Full credit for your logic! It might work but in the meantime hasn't the enemy really beaten us at our own game? While we move the distance to an alternate site compatible with safety and surprise, we are out of action and the enemy's maneuver element has moved frighteningly close. Besides, the enemy is probably tracking our tell-tale dust anyway and our alternate position will prove as uncomfortable as the one in the first instance.

Why not forget about the alternate position and break contact to a pre-selected position to the rear to contain any break-through? This is reasonable if we are willing to accept the fact that our major anti-tank weapon has been good for only one shot during a critical point in the battle. Of course, the psychological impact on the front line "snuffy" when he sees his major AT unit heading for the rear in the face of an armored attack might be a matter of concern. Also, in open country, our M-50 might be degraded with an enemy shot in the back during this rearward movement. And what about this open terrain, this rolling countryside so favored by a fire and-maneuver tank attack? Here we have our greatest Ontos liability. Our primary AT weapon sits basking in all the glory of its 1800 yard effective range while the opposition tanks crack away at us at ranges considerably in excess of ours. They are damaging us with their tanks long before we can employ our anti-tanks against them. Better lay the artillery for direct fire, Marines!

Perhaps I'm unfair. I set the scene for the illustration and naturally it tends to support my views. How about a situation favoring Ontos employment? Consider close country where range counts for naught? How about the ambush capabilities of Ontos. Unsurpassed, are they not? The answer is quite so. It is a close country anti-tank weapon; it is an ambush weapon and little else, and this is the point. The Ontos violates the principle of economy of force. It is an expensive weapon restricted only to situations which favor its limited capabilities-defensive capabilities of ambush and short range. Does this return warrant the expense in terms of dollars, personnel, support and maintenance effort necessary to sustain an Ontos-equipped battalion? I say no. Leave the short ranges to the BAT*s and provide the AT battalion with a weapon which has the range and ruggedness to do battle with tanks before the infantry has to cope with them.

Bernard E Trainor**

218 Cordoba San Clemente, Calif. –

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*BAT = Battalion AntiTank [system] = 106mm RR in that time frame. It was a trilateral program [US, UK, CA]. Thank you for this definition Dr. Ken Estes, USMC(Ret.) who is a Foundation Board Member, oft-published author, and has contributed significantly to the discussion of the Ontos.

** Retired Marine Corps Lieutenant General

Little Orphan ONTOS

by1stLt. William J Lannes III

Marine Corps Gazette (pre-1994); Aug 1963; 47, 8; ProQuest Direct Complete Pg. 41

It may surprise you to learn that many Marines don’t understand Marine Corps weapons. This is particularly true of our supporting arms and especially true of ONTOS. Most Marines know about the great armor-defeating qualities of the 106mm recoilless rifle and its accompanying (and undesirable) back blast. They also know that the ONTOS has good cross country ability and offers some protection against small arms. Few Marines, however, know how to use the weapon properly and even fewer have confidence in what it can do. This is appalling because ONTOS is the Marine division’s primary close-in antitank weapon.

In my view, ONTOS is a good weapon. This opinion is based on my experience with the weapon while serving with the 3d Antitank Battalion on Okinawa. When first assigned, I was apprehensive. I didn’t hold the weapon in high esteem. Fortunately, I joined a group of Marines who were dedicated to proving the worth of the ONTOS. To our surprise and relief we found that, for its intended job, the United States has no finer weapon. Neither I nor my colleagues, however, ever felt that ONTOS was the ultimate-there is much room for improvement.

ONTOS was adopted to replace the antitank function formerly carried out by tanks organic to the division. However, the very first thing to understand about ONTOS is that it is in no way, shape or form a tank. That statement may sound silly to some, but it is amazing how many Marines think of ONTOS as a tank. They say it can’t stand up in slugging match with a tank because its armor protection is insignificant. ONTOS was never intended to outslug anybody-it is not an armored vehicle. ONTOS is in the same class as the Army “Scorpion” (90mm gun on tracks) which has no armor at all. ONTOS crews realize that the vehicle’s thin steel plating will only stop shrapnel and small arms. They also know small arms can affect the weapon’s efficiency because of its vulnerable hydraulic system.

Because of the characteristics of the 106mm recoilless rifle, too many Marines feel that ONTOS is good for only one shot before the show is over. It is surprising how few people apply fire discipline, which they have taught or been taught throughout their careers, to larger caliber weapons. Fire discipline plays a major role in antitank outfits of any kind. In tank defense, ONTOS never fire all at one time. Generally, the light section (two vehicles) opens fire when the tanks are in range. Each vehicle can fire aimed shots on different targets in a matter of seconds. As the light section moves back to reload and into its alternate position, the heavy section (three vehicles) picks up the fire on the remaining tanks. When the tank crews have adjusted to this new enemy fire, they find only fleeting targets and are met by fire from the new position of the light section. Depending on the type of action being fought and the situation, variations of this tactic can be used. Good crews and close teamwork are required. However, after practice and training, the 3d Antitank Battalion proved ONTOS to be effective against tanks. How? By putting the tankers’ reaction time and maneuverability against those of the ONTOS crews.

Proper training enables ONTOS crews to adapt to various combat situations. Because of the vulnerability of the ONTOS, antitank units should work at night whenever possible. Just before dark, the vehicles should be parked in an assembly area, taking normal precautions as to distance, camouflage, and defilade. The dismounted crews then go forward on foot to examine the terrain they are to defend. Each position should be determined (both primary and alternate) and routes to and from them should be mapped out. When the positions are selected, the crews must insure that they can find their positions in the dark. During the night the vehicles are brought forward and the crews then prepare their positions (in many cases this requires extensive digging). All work must be completed by dawn so that movement will not give away the positions to enemy ground or air observers.

Principles of Camouflage

In night operations, coordination must be effected with the infantry unit responsible for the area. The infantry must supply security for anti-tank units. Variations of this procedure depend on the situation. Whether the unit is in a position or on mobile defense also affects the selection of positions. In all cases, however, camouflage must be completed by morning. It is essential that the enemy does not locate the ONTOS defensive positions because of the greater range of tank and artillery guns. Surprise is one of the primary considerations in antitank operations.

Understanding the principles of camouflage and terrain analysis is important because the ONTOS has to operate in all types of terrain. Many Marines have expressed concern about the terrain in which the ONTOS will be forced to operate. They are particularly dubious about open terrain, which is considered the best tank country. This rolling tank terrain offers enough protection for the highly maneuverable ONTOS. In the Mt. Fuji training area, where our overseas tank units do a great deal of their training, tanks and ONTOS were pitted against each other. At the start of the exercise, the tank battalion was spread out at one end of the problem area. The terrain was such that with the aid of field glasses the tanks could be seen for many miles. The night before the problem began, the ONTOS units had moved in to occupy the forward defensive area. Thus, on the morning the problem began, the ONTOS units were in position waiting for the tanks. When the tanks came within range the ONTOS fired (blanks from the 30 cal. machine guns) and began leap-frogging to various positions, both lateral and in depth. Using knolls and cuts, the antitank units were able to keep generally out of the line of sight of the advancing tank.

The biggest problem the ONTOS had was with the aircraft employed against them. The planes would occasionally catch an ONTOS moving on the road and would make runs on it. The antitank units had no air support during the problem; therefore, the tanks were not harassed by air attacks.

An important aspect of the antitank operation was mutual support and depth. All of the ONTOS moves were covered by positioned vehicles. In short, the men understood the weapon, used the terrain to their advantage, and came out ahead as a result.

The results of this and similar field problems certainly indicate the worth of ONTOS. However, there are still Marines who refuse to accept any weapon that hasn’t been combat tested. Some Marines concede that ONTOS may be useful for close-in work but they shudder to think of operating against large scale tank attacks launched at great distances. Let’s not get our thinking out of focus. Certainly ONTOS is our primary antitank weapon but it’s not the only one. Anti-mechanized plans include all supporting arms with tasks assigned according to the capabilities and range of each. If the Marine Corps should find itself in a big land campaign in wide open territory against large tank attacks, then the ONTOS will play an important, but not exclusive anti-mechanized role. Those enemy vehicles that do get as close in as the ONTOS sector will find it tough going.

The ONTOS also has limited offensive capabilities. However, in considering its offensive role, the weapon’s limitations must be emphasized. ONTOS’ primary mission is to provide direct-fire support for infantry units.

The most important thing to remember about ONTOS in support of infantry is the weapon’s vulnerability. No squad leader would use a flamethrower without giving the man carrying it the fire support needed to enable him to maneuver to a relatively safe firing position. This same thinking must be applied to the ONTOS. The unit that calls the ONTOS up to knock out a pill box must give it fire support. Then the weapon can maneuver to the least vulnerable firing position to deliver its devastating payload.

ONTOS can be used in various fire support roles if not subjected to heavy concentrations of large caliber or small arms fire. Of course, everyone is expected to take risks- and ONTOS crews are no exception-but let’s not sacrifice our antitank capabilities unnecessarily.

The ONTOS is certainly a controversial weapon. That it is expensive and has faults is undeniable; but for the purpose designed it is the best we have in the field. ONTOS was never intended to be a long range, armored vehicle. Its function is the same as the vehicle mounted 106mm recoilless rifle except that it can do the job much better. It is much more maneuverable in all types of terrain. In fact, there were many times when our ONTOS retrieved 106s bogged down in mud.

Superior to Tanks

The ONTOS also is superior to tanks in snow and mud. It has tremendous initial firepower and an excellent firing and sighting system. It is not so dependent on its 50 cal. spotting rifle and can use burst on target with deadly effect. ONTOS’ parallel communications system offers a means of flexible control. Such factors combine to give it much more staying power than our other antitank weapons. This staying power is not to be confused with “slugging it out”. ONTOS can stop tanks by tactics and firepower, giving up only minimum ground or none at all.

It is important to remember that the ONTOS is not a tank. It is a tank-killer. Most of us are not anxious to climb into the ring with a professional boxer. If we met one man on the street, however, and stabbed him in the back, he would be just as dead as if we had met him on his own terms. That’s the way it is with ONTOS.

It is important that our supporting arms be used correctly and their efforts coordinated. The more our leaders understand and use their supporting arms the better the Marine Corps will be. Those who have a chance to work with ONTOS should use it to full advantage. It is the least understood and most abused weapon in our arsenal.


M50 Ontos: The Forgotten Tank-killer

By Brendan McNally - February 12, 2013

Frontal view of the M50 Ontos and its Marine crew during Operation Franklin in the Quang Ngai province of Vietnam, June of 1966. (U.S. Marine Corps Archives & Special Collections photo)

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It is the tradition in the U.S. Army to name its tanks after great generals. Over the years there has been the Stuart, the Grant and Lee, the Sherman, the Patton, the Pershing, the Abrams, the Sheridan, the Chaffee, and the Bradley. But there was one armored vehicle that was so singularly odd and strange looking; it didn’t get named after anyone, lest perhaps, some insult might be taken. Instead, the name it got handed was Ontos, the Greek word for “the thing.” It was an apt name. With its tiny chassis, tinier turret and six, massive, externally mounted recoilless rifles; the M50 Ontos had to have been the strangest armored vehicle ever to make it into the American military inventory.

Except for some Marine Vietnam veterans, the Ontos is, today, almost wholly unremembered.

A M50 Ontos during a training exercise at Marine Corps Base Quantico, Va., Dec. 19, 1955. U.S. Marine Corps Archives & Special Collections photo.

The reason has less to do with the Ontos’ battlefield performance, which at times was stellar, than it did with the fact that only about 300 were ever built, a little more than half of which survived up to the time of the Vietnam War. It meant there weren’t enough Ontos to engage the tactician’s imagination and so it never featured in tactics problems in the basic schools. There was never a military occupational specialty for Ontos crews. Officers might serve in an Ontos unit for a tour, but then they’d move on to something else and whatever they’d learned from it never really entered into the institutional memory. Another reason was that Ontos was designed as a tank killer, but since the North Vietnamese Army (NVA) only rarely used tanks, Ontos was used mainly as an ad hoc weapon.

But fight it did, distinguishing itself at Hue, Khe Sanh, and countless other battles. For all its out-and-out eccentricity, Marines found it handy to have around because it was nimble and fast. Thanks to its relatively light weight, Ontos fairly glided through swamps and rice paddies, where heavier vehicles wisely feared to tread. And Ontos packed a punch that was way beyond its weight class. For this reason, the NVA feared it and avoided the Ontos wherever possible.

If there was a general after whom the Ontos should have been named, it probably would have been Lt. Gen. James Gavin, wartime commander of the 82nd Airborne Division. After the war he wrote a book called Airborne Warfare, outlining his vision for using airborne forces in future wars. Part of it involved using air-transportable mechanized forces as a kind of light cavalry, capable of doing reconnaissance, and when necessary, laying extremely deadly ambushes against enemy armor. In the spirit of cavalry, such vehicles would have to sacrifice protection in favor of speed, agility, and ability to deliver serious firepower.

The Ontos program began in November 1950 as a joint Army-Marine Corps program. The development contract went to Allis Chalmers’ Farm Machinery Division, with the work being carried out at the company’s Agricultural Assembly Plant in LaPort, IN. According to legend, the spec sheet they developed it from was only one-page long. Among the few things that it specified was that its running gear would be based on the M56 Light Anti-Tank Vehicle and that it would utilize the same six-cylinder, inline gas engine common to all the military’s 2½-ton GMC trucks.

In 1953, the prototype was presented to the U.S. Army, and they immediately hated what they saw. They hated that it was so small and too tall and that there was not enough room inside it, either for the three-man crew or for ammunition for the recoilless rifles, of which only 18 rounds could be carried. They didn’t like that the turret was so shallow, really little more than a cast steel turntable and hatch in the middle. They hated that the six recoilless rifles that made up its armament were externally mounted and had to be reloaded from the outside. They didn’t like that the half-inch armor plating on the sides wouldn’t protect the crew members from anything larger than .50 caliber machine gun rounds, and that the underside’s armor plate was not even half that thick, making it totally vulnerable to mines or anything that might explode underneath it. The Army backed out of the project, canceling their share of the 1,000 vehicle order.

Two M50 Ontos from the 1st Anti-Tank Battalion move up to support a 2nd Battalion, 4th Marines patrol in the Quang Tin Province of Vietnam during Operation Iowa. U.S. Marine Corps Archives & Special Collections photo.

The Marines, on the other hand, were not nearly so fussy. They liked that Ontos was so fast and agile and seemed capable of going anywhere they went, which was more than could be said about most tanks. They accepted that instead of being able to fight it out with enemy tanks, the Ontos would have to “shoot-and-scoot” to a place where it could safely reload. As for its pronounced lack of protection, they shrugged. For Marines, being shot at was nothing new. They placed an order for 297 Ontos. The production contract went to Allis Chalmers, which started building them in 1955 and finished in 1957, with the first vehicle accepted by the Marine Corps on Oct. 31, 1956.

The Ontos’ official name was: “Rifle, Multiple 106mm self-propelled M50.” At its heart was the M40 106 mm recoilless rifle, a weapon which had been developed after World War II as a tank killer, based on the earlier M27, 105mm recoilless rifle, which turned out to have a number of key deficiencies. The rounds the M40 fired were not, in fact, 106mm, but 105mm, but were designated as 106mm to keep from being confused with the M27’s round, which was not compatible with the M40. The M40 had the accuracy, the range, a serious punch forward and a serious kick aft. During the Ontos’ testing at the Army’s Aberdeen Proving Ground in Maryland, all six guns were fired at once and the backblast was so great that it knocked bricks out of nearby buildings and shattered numerous car windows.

The powerful recoilless rifles’ accuracy was greatly aided by attaching .50 caliber spotting rifles to four of the Ontos’ six M40s. The rifle fired a tracer round whose trajectory, at least for the first 1,100 yards, was nearly identical to the M40s, and it marked the spot it hit with a visible puff of smoke. The spotting rifle’s own range was only 1,500 yards, and hitting targets beyond that required burst-on target and bracketing techniques of fire adjustment.

A M50 Ontos fires at snipers along the urban streets of Hue during the Battle of Hue City, 1968. The Ontos proved its value during the Tet Offensive. U.S. Marine Corps Archives & Special Collections photo.

The first time Ontos was deployed was during the Lebanon Crisis of 1958. Since it was a peaceful intervention, it saw no action. Six years later it did go into combat during the American intervention in the Dominican Republic of 1964. There it encountered and promptly destroyed several enemy tanks, including a French-built AMX-13 and an old Swedish L-60. It was the only time the Ontos ever performed the mission it was built for.

Then came Vietnam. In 1965, during the initial American buildup, the Marines sent over two anti-tank battalions equipped with Ontos. With no enemy tanks to fight, the Ontos companies were quickly spread out and attached to other units. The problem was, with no doctrine in place for them other than for fighting tanks, the Ontos were used or not used largely according to the whim of the commander of whatever units they were attached to.

Though they quickly proved themselves as highly capable infantry support weapons, providing excellent frontal fire and flank protection, the Ontos had some serious shortcomings. After one or two would get destroyed by mines or rocket-propelled grenades, their unit commander often found his enthusiasm for them considerably dampened and relegated them to static defense duties. Another problem that plagued the Ontos was repeated accidental firings of its recoilless rifles because of too-tightly adjusted firing cables.

Even so, the Ontos continued to be deployed supporting infantry. Using HEAT rounds, the Ontos was an excellent bunker-buster. But where it truly excelled was as an anti-personnel weapon. A “beehive” round was developed for the M40 that, upon exploding, unleashed a massive whirlwind cloud of nearly 10,000 steel flechettes. As a result, the VC and NVA were terrified of the Ontos and avoided it wherever possible.

A M50 Ontos leads commandeered vehicles during the Battle for Hue City, 1968. The Ontos was spearheading the effort to MedEvac and resupply Marines in Hue during the Tet Offensive. U.S. Marine Corps Archives & Special Collections photo.

In December 1967, the Marines reorganized their anti-tank battalions and as a result, the Ontos units were all attached to tank battalions. By this point, the Ontos was becoming worn out. Treads and other replacement parts were becoming difficult to obtain. Increasingly, Ontos were being cannibalized to keep others operating. It was already obvious its days were numbered. Then, on Jan. 30, 1968, the NVA launched the Tet Offensive. It was one of the longest and bloodiest battles of the entire Vietnam War, nowhere as hard fought as in Hue City.

For the Ontos, the battle was its shining moment of glory. After the American (2/5) and South Vietnamese forces cleared the south bank of the Perfume River, the 1st Battalion of the 5th Marine Regiment (1/5) reached the Citadel. A number of Ontos were brought up and one by one, began taking out the buildings where the enemy were holed up. One of the Marine officers leading the siege of the Citadel later identified the Ontos as “the most effective of all Marine supporting arms,” in the Battle of Hue. At the same time, the NVA siege of Khe Sanh was also under way. With the threat of NVA armor anticipated, 10 Ontos were airlifted into Khe Sanh by MH-53 helicopter, and incorporated into its defense. There, the Ontos also performed with distinction.

A year later, the Marines deactivated their Ontos units and the vehicles were handed over to the Army’s light infantry brigade. The Army used them until their parts ran out and then employed them as bunkers. What happened to them after that is largely unknown.

After Vietnam, some were handed over to civilian agencies and used as forestry vehicles. A tiny number made it into collectors’ hands. Some are in museums. According to Mike Scudder, a former Marine who owns several, there are more World War I tanks in circulation than there are Ontos. This may not actually be true, since there are believed to be more than 60 Ontos sitting discarded in the desert on a Marine Corps reservation near China Lake, Calif. If they are still there, no one is saying.


Oral History Interview of 1st Lt. Robert G. L’Heureux, USMC, Which Describes ONTOS Operations South of Marble Mountain, Republic of Vietnam During September, 1965”

While in Vietnam I was assigned to 3rd Tank Battalion Platoon Commander from June –Oct 1965, which I was evacuated in Oct and when I returned I was assigned to headquarters Battalion 3rd Marine Division for duties as Security Platoon Commander. While with the Tank Battalion I was located principally about 15 miles south of DaNang across the Tourane River. While Headquarters Battalion Commander, I was located approximately 10 miles NW of the airstrip itself in DaNang and the area of CP. The only major combat action the Battalion, largest size that I can remember or participated in was as said earlier was with the 1st Battalion 9th Marines in Operation GOLDEN FLEECE in the fall 1965. It took place in the Marble Mountain area. Purpose of the operation was to deny tank gathering operation of the Viet Cong during the rice harvesting season, this extended operation took place over a 2 week period in which a great deal of patrolling activity and almost daily sweeps were conducted throughout the same areas to remove any infiltration by the VC in the rice harvesters. Generally what would occur in operation commenced at dawn or earlier and the area would be swept of all indigenous personnel would be taken to collection points usually by AmTrak or if it was close enough, they were marched there. They were treated according to the way, generally, acted when they were picked up. They were then interviewed by the District Chief and his team of policemen, I suppose they were. The VC suspects were separated from the rest of the populace. The people who were declared innocent of any connection with the VC were generally treated to a series of lectures and films on rice harvesting. General propaganda, lectures given, a number of pamphlets and perhaps small amounts of rice and things like this to compensate for their loss of time since they were secured from their rice harvesting by this operation. It was generally considered to be successful. There was a minimal patrol type of contact and one larger contact that took place with Alpha Company one night. The operation, in general, occurred in the villages we were in Sept 1965. A villager ran into to see the District Chief, who was living at that time adjacent to the 1st Battalion 9th Marine Battalion are, right underneath Marble Mountain, and informed the District Chief that a VC Battalion had moved into his village and had declared that they were there to fight the Marines. Their actual purpose was, I supposed to collect rice as taken their duty from the populace. This word came in about 0800 and at about 1230, the operation had kicked off. Under the command of the Alpha Company Commander with 2 attached platoons from Charlie Company 1st Battalion 9th Marines, ONTOS platoon and a tank platoon Bravo Company 3rd Tanks. The operation was a sweep Marble Mountain south until contact was made. Contact was made approximately 1 1/2 hours later with the 2 platoon from Charlie Company were on the right of the sweeping front. Alpha Company extended the rest of the way toward the left flank, ONTOS screen by themselves from the beach and connected with the last infantry platoon in the left flank. The tanks were spread out to support through the three. Alpha Company platoon were generally in the middle of the sector. Originally I divided the line perpendicularly which caused later when one of the platoon from Charlie, lead by Lt. Gerald Robbins came under fire in a rice paddy and the other for some reason, there was no radio contact was made and Company Commander was unable to determine just exactly what was going on or if anything was going on. The ONTOS platoon that I had, for some reason had contact all the way on the other side of the company front. We moved in support them we had to cross the ridge line and go down into the rice paddy. When arrived in the rice paddy, nothing was going on at all, the tank that was originally with us but couldn’t stay because he could not navigate the rice paddy. He left, I don’t know where he went. About 4 or 5 minutes later, some HE’s were going off in the area. At first it was thought to be 80 mm mortar fire but since the rounds were landing in almost the same place, it was determined that it must have been 3.5 or 57 mm recoilless rifle.

Question: Is this a friendly one?

L’Heureux: This was not friendly at all. This was also coordinated with a great deal of machine gun fire spreading out in the area.

Question: This is Viet Cong fire, right?

L’Heureux: Yes sir, up to this time we still had not made any contact with the infantry platoon that was there. Radio contact was sporadically…

Question: Were you out there by yourself at this time? You were not being supported by the infantry, is that right?

L’Heureux: No sir, that’s not correct. We were screening left flank of the whole company front along the beach and we swung…..

Question: You were accompanied by infantry…

L’Heureux: We were trying to hook up with them since we knew difficulty knowing no one else could make contact with them. I had no contact with the Company Commander of Alpha Company myself. There was big radio foul up. Generally it was about 15 minutes before we contacted the infantry, who turned out to be laying in the rice, apparently waiting for the rest of the company to come to their support.

Question: There were two platoon of Charlie Company? One platoon of Charlie Company and your ONTOS.

L’Heureux: One platoon of Charlie Company. Yes, Sir.

Question: Did you attempt to establish communications through your channels with the Company, infantry or Platoon leaders?

L’Heureux: Yes sir, there was no communication to be had. Whatsoever.

Question: You said earlier that you had contact with the entire operations, is that right?

L’Heureux: Originally

Question: I see, but then it failed after you were separated from the rest of the operation by the ridgeline.

L’Heureux: Yes sir.

Question: Couldn’t raise the tanks? Couldn’t raise …

L’Heureux: We could raise the tanks until we moved down into this valley..

Question: No communication other than the platoon you were with and ONTOS?

L’Heureux: We had inter-vehicle communications and I had contact with the Platoon Commander from Charlie Company that had originally gotten into trouble.

Question: What kind of radio did the platoon leader have?

L’Heureux: PRC10. We were netted and even that communication wasn’t too good. It was very sporadic. Mostly communication was carried out by hand and arm signals. Occasionally I’d have to get out from the vehicle to talk to them and all this time there was a little bit of fire going on. It increased steadily but we came out and were in the process of being surrounded and we got a little bit apprehensive. Up to this time the 50 or whatever it was, the 3-5 that had been firing at us the fire was returned by the 106. Apparently which was halted, pieces of what were probably 57 mm recoilless rifle rounds were found the next day in that area. The fire kept up for about 4 hours. A platoon from Charlie Company took about 8-10 casualties as I remember. At the time we left, the counter attack was broken off slightly and that platoon was entirely out of machine gun ammunition. Later Lt. Robbins told me they were down about 2 magazines, 2 M14 magazines. We didn’t have any machine gun ammunition to give them. Some of our 30 caliber were inoperative in that they would only fire about 3 rounds at a time due to the fact that the bolts were old, spare bolts were just as old and chipped. So if the bolt was falling out, and it usually was the bolt, the only thing to do was to change the bolt and hope the other bad ones worked too. Which occasionally happened, it was difficult to do under fire but we supported the best we could. We didn’t fire a whole lot of 106’s because the general plan of the sweep was the company to close around whichever platoon was hit first in an attempt to enclose whatever forces contacted them. Since we had no contact with the Company Commander, the only assumption we could make was that the rest of the company was closing in around. We didn’t want to fire in fear that we’d be firing into our own lines, after a while it became obvious there were no Marines around us so we fired 4 or five rounds from there. Probably the radio communications went really bad at the time the fire became the heaviest due to the large amount of rain that started falling. This obliterated everything. Sight you just couldn’t see further than 25 or 30 feet, it rained so hard.

Question: Speaking of communications, was there any way you could communicate back to the Battalion or Command Post for air support or additional equipment?

L’Heureux: Only through the Battalion tactic net, sir, as I said.

Question: You could not do that, is that right? No communication with anyone….. Other than with the platoon and the ONTOS, alright.

L’Heureux: No sir. I suppose I remember about 4 hours after the action initiated, it slacked off slightly and Lt Robbins wanted to keep contact because he still assumed that the Company would try to finish and enclose that force that had contacted. Just about that time, radio communications started to come in. I was monitoring another platoon from Alpha Company; somehow we had gotten word where the rest of the Company was. They had found a large rice cache in a village on the other side of the ridgeline surrounding that and were attempting to wait and make the VC come and fight for the rice. They were, the Company Commander was a little apprehensive about where his platoon was. He was real glad to hear it was still around and he also didn’t know where the ONTOS platoon was. So I took my ONTOS and another and a number of casualties back across the ridgeline, back over to where the Company was deployed.

Question: How did you carry the casualties?

L’Heureux: Set them on the arm plate.

Question: Externally, right? How many did you carry on the ONTOS?

L’Heureux: 4 on each one

Question: How seriously were these men injured?

L’Heureux: Not very serious. The worst I remember was shot right through the elbow. He was in pretty much pain. He was the most severely injured one.

Question: Were you accompanied by anyone when you returned with these two ONTOS?

L’Heureux: No sir. The Company Commander then or Alpha Company told us to go back and get into firing position and attempt to have Lt. Robbin’s platoon extracted from the area since he was unwilling to leave that much rice there. As I remember, about 5000 pounds and he didn’t want to leave it because he was pretty sure they’d come and snatch it away. As I remember, in the village there was nothing but old men, women and children. Even old women, there were no young women in the village. I did as he said, we went back and extracted all the ONTOS, I called the rest of the ONTOS back from the rice paddy with Lt. Robbin’s platoon with the explanation that he was to walk up the ridgeline with John and let us know when his people were clear of the treeline, mostly bamboo and pine on the other side of the rice paddy where he was taking most of his fire from. The contact was increasing generally; apparently they knew it was a pretty small force there. He withdrew finally on the side and fired up the remainder of the ammunition except 2 rounds of the 106 ammunition that we saved for each of the ONTOS for the march back to the Battalion area later on that night. We fired into the treeline, about 50-75 feet above ground level.

Question: At what distance?

L’Heureux: This is about 400 meters, I would say. We fired, we were up off ground ourselves along the ridgeline, it was about the only place we could get. Matter of fact, we had our back against thatch huts. Clear the people out of their huts. Their huts were destroyed as a result; it was the only decent firing position. Matter of fact, it was the only firing position available at all. The rest of the march was….

Question: What success when you said you fired into the treeline, did the infantry later move into the treeline, what where the casualties?

L’Heureux: The area was swept out again the next day. At that time, as I remember, about it was about late in the evening 10 or 11 as I remember, and the orders that came from the Battalion despite the Company Commander’s request was to stay and see what else he could do. His orders were to return, since it was a comparably small force. His orders were to return and destroy the rice before he came, which he did.

Question: I see, what I’m interested in though, what affected your 106 firing into the treeline? You said the following day that the area was swept and there they found parts of bodies. About how many?

L’Heureux: They said about 20 bodies were there.

Question: In your estimation and from the observation of the bodies there looked like they had been sustained from your 106’s, is that right?

L’Heureux: As I remember it was described to me that a lot of bamboo splintered in the bodies and bodies that were just ripped apart.

Question: How many rounds did you fire at this treeline, roughly?

L’Heureux: As I can remember, we fired about between 6-8 from each ONTOS into the treeline.

Question: So in other words, you fired about 30 rounds, single shot. I see. What did you aim at?

L’Heureux: Yes sir. Generally speaking… It was just light enough to see to distinguish the treeline from the rest of the rice paddy. Generally top of the treeline and tried to split it across from where the muzzle flashes were coming from.

Question: I see, in other words, you tried to cover the area and you aimed at the areas where the muzzle flashes were.

L’Heureux: Yes sir.

Question: What kind of rounds did you fire?

L’Heureux: We fired high explosive plastic tracer around.

Question: I see, then these rounds were detonated when they struck the trees and bamboo and the splintering effect from the bamboo caused additional casualties, is that right?

L’Heureux: That was my understanding

Question: Did you personally go up and look over this?

L’Heureux: we were on another sweep

Question: I see, well who did you get this information from?

L’Heureux: As I remember the VS2 gave out some of this information in a briefing the next day and I received from of this from a phone call.

Question: But in your opinion and to your knowledge, there was no other type of weapons or no infantry that fired into the area.

L’Heureux: There was a lot of artillery fired in the area, later on. As the march back, we attempted to cover on the flanks and the rear with artillery so we could get back.

Question: So it is possible that some of these casualties could have been sustained from the artillery fire.

L’Heureux: Yes sir, that is very possible. The march was without incident. There were 2 tanks abreast in the front of the column, 2 tanks along the left flank of the column, 5 ONTOS along the right flank of the column and 5 columns of infantry composed the column.

Question: Okay, I think we’re through with this part.

L’Heureux: The rest of the Operation GOLDEN FLEECE was, I remember were patrol action, as I said, daily sweeps, generally Company sweeps and accompanied blocking positions. ONTOS were used both with the moving element and blocking positions, depending on the terrain, traffic-ability and the size of the force, of the sweep force. Patrol tactics in Vietnam that I had knowledge of stemmed from….

Question: Just the ONTOS…..

L’Heureux: Just the ONTOS. Patrolling activity with the ONTOS was very very scarce. Generally went out with platoon size patrol or larger combat patrol. Where they were used generally as needed, although not too much was done because it was inconvenient for the most part. I know that the tanks were used a great deal to carry infantry on patrol. Search and clear operations would, generally, block reinforcements would be moved in the Marble Mountain area, south of it by armored column using AmTrak and troops mounted tanks moved in rapidly before daylight to be in a blocking position before the sweeping element would commence. Sometime helicopters were used. The ONTOS tactics had to be evolved, generally although they were similar to tank infantry tactics. A number of the tank infantry techniques could be utilized though mainly the back blast of 106 recoilless rifle and the lack of a tank infantry phone on the ONTOS would be very helpful thing to have. Although it would have to be mounted in a different place. It would greatly expedite communication with supportive units since the visibility from the ONTOS is scarce to nonexistent. At the time and the only opportunity it had to determine what time of terrain it would cover and location of any target was to contact men on the ground. Generally the tactics were that the ONTOS would follow a line of infantry advancing from about 50 yards behind. Tried to maintain contact with one fire team on an individual and almost physical contact. With the fire team to maintain their position and formation as best they could. And this fire team would generally be far enough in advance to scout out any terrain, deep pits or obstacles that would be difficult to traverse. And they would also check out things in order to give us some idea about where we could go and how to get there. As far as firing went, high explosive plastic tracer was almost exclusively used due to the fact that it went off easier since it was detonated on any number of angles, where inner tack almost had to hit a hard surface and point detonated. You could get the plastic tracer around and expect it to go off in any reasonably hard ground, even sand. It would go off after but the heat rung would not do this, it was just generally be a dud unless you hit something very hard such as a bunker of something like. Which it was used, it was suggested at least two heat rungs would be carried in each ONTOS and I understand, this was later done for the express purpose of eliminating bunkers and any hard type targets. As I said, the patrolling activity of the ONTOS was scarce and nonexistent.

Question: Speaking of ammunition, will you elaborate any recommendations you have for any other type ordinates?

Question: Speaking of ammunition, will you elaborate any recommendations you have for any other type ordinates?

L’Heureux: Well, from the majority of the Platoon Commanders and ONTOS that I’ve talked to, and my own feelings are that a white phosphorus rung would be of great benefit. Due to the fact you could see the area, the casual radius a lot easier to cover the target and correct off your initial burst on target with a phosphorus rung. Also there’s a lot of discussion about a tank type canister rung which would be able to be used… well there’d be no limit on their amount of use. Develop some kind of… not to harm the rifle in any way. This would be a great advantage especially in the heavy underbrush and thinks like this where the ONTOS could actually get right in there and get close enough to fire, almost directly such as a shotgun. Whereas with your AT rounds of the ONTOS you don’t really care to get too close in the impact area at all. I think with a canister type round, developed especially for that area, you could really give a great deal more support, matter of fact it would become possible to get in front of the support infantry, in all. You’d have to be quite a ways in front about 150 yards to be safe in any way. An area could really be reduced effectively almost point blank range.

Question: Alright Lt, will you tell me what success you had in crossing rice paddies when they were flooded?

L’Heureux: It took a while to develop the drivers themselves. They had not spent much time in rice paddies, as a matter of fact, we had no one that had spent much time in any of that type of terrain with the ONTOS. Drivers developed rapidly, it soon became obvious that what would stop an ONTOS was just a hill too steep to climb or a jungle too think to penetrate at all. Almost any rice paddy could be navigated if the terrain had not been chewed up previously by AmTraks. They created great mounds of mud, I think due to turning on an axis. Their tracks turned large stacks of mud. This would block us by getting caught in the tracks and guards and generally jamming everything up. If we were allowed to go first, we could traverse any rice paddy I saw.

Question: And climb out?

L’Heureux: Yes sir. Generally the best tactic we found, as I remember, it was in the book, was to just keep moving. If you stop you were sure to get stuck or darn close to get stuck. We moved all the way through the rice paddy until you hit hard ground again or a section or a section of the rice paddy that wasn’t flooded. We had no difficulty whatsoever.

Question: How quickly did you move through the rice paddy?

L’Heureux: The actual speed was 3-4 miles an hour

Question: By walking speed

L’Heureux: Yes, all in low gear

Question: Describe the action in the village when you went in unsupported.

L’Heureux: That occurred in late August 1965 or very early September. We were attached to 2nd Battalion 9th Marines, principally Hotel Company. Our mission was to go with Hotel Company, as I remember they were sweeping the Kam Na Complex which is more or less cut off from the regular land body by a river extending on one side and a very deep stream on the other. Our mission was to try to find a crossing path through the stream to get into the complex and support Hotel 2-9 during their sweep. Attempts had been made before I had understood to get across there and they said just do what you could. See if you can get in there. Both sides of the stream were very thick foliage, bamboo maybe 18 to 20 inches around, extending pretty high. We weren’t able to find a place to cross and we were told just to stay in the salt flats adjacent to the Dong Song 3, as I remember across the railroad tracks and generally patrol around there to keep anybody from coming along behind the Battalion disturbing us during the sweep. While we were there, we received word from the 2nd Battalion 9th Marines Command Post to proceed, I think the village’s name was Lis Song, although I’m not sure if that’s what it’s called. Right south of Dong Song, the next village. I had 4 ONTOS at that time operative, we were told to go in there and generally check the village out to see if there was anything there.

Question: By yourself?

L’Heureux: Yes, by ourselves. We had no infantry with us at all.

Question: How large was the village?

L’Heureux: I’d say there were abut 25-30 structures in the village, about 3-4 person size. The railroad tracks ran right through the village, right down through the middle. We travelled on the railroad bed for the most part. As we entered the village, the lead ONTOS observed 15 or 20 men running from the other end of the village and it appeared to be carrying weapons. He was given permission to fire and did so. Although the majority of the fire that took place was from the 30 caliber machine gun as usual, since at that time, as I remember, confirmation was needed from the S-3 Battalion Commander to fire the 106. When all was said and done the first 106 round was fired. One ONTOS later reported that he had run one of the men down, he just literally ran over him and as I remember, 26 or28 bodies left when we finished. Then men had been running and jumping to a hole in the ground, apparently a tunnel complex out there. After that was reported, we came back into the village and it soon became obvious that there was a rather large tunnel complex that extended all the way underneath the village. One of the ONTOS in turning around had collapsed part of the tunnel and had fallen in a large pit of his own making due to the collapse. The rest of our activities were literally flattening that village while it was reported later It didn’t occur to us that later we were over extending ourselves due to not having any infantry support whatsoever at that time. And later on we hooked up again after sweep with Hotel Company and spent the night.

Question: Going through the village, I understand that you raced through it and went around all the little streets, at what speed?

L’Heureux: Genneraly went pretty fast, about 20 miles an hour.

Question: Were you firing your machine gun at this time?

L’Heureux: No sir, it was all very very close, just packed in there.

Question: Were you receiving fire as you raced through it?

L’Heureux: No sir, there was no fire.

Question: As I understand, your vehicle did start them collapsing these tunnels, is that correct?

L’Heureux: Yes sir, there was an area, I’d say as large as 3/4 of a football field, something like that.

Question: I see, Was this village later checked over by the infantry?

L’Heureux: As I understand, it was sir. The people went in there and examined the tunnel complex, in their opinion was, just a local complex for the protection of the villagers and the village itself from any fire that was going on in the area. Because of the fact that it was dug very deeply, most of the VC tunnels found were just under the surface.

Question: Were you in communication with the Battalion CP at the time you discovered the first group of Viet Cong?

L’Heureux: No sir, not at that time. Communication was reestablished immediately there after.

Question: I see, was there any, was the Battalion 3 or CP giving you any instruction as to wether you were to withdraw or remain there?

L’Heureux: No sir, we recorded it and they said just to complete checking out the village and return back to the salt flats by near Dong Song.

Question: How far away was the Battalion Command Post?

L’Heureux: It was all the way across the river, sir about 6 miles.

Question: I see, would it have been possible, do you think, if you had had communication to call for helicopter patrol to check it out?

L’Heureux: Anything is possible, but at the time communications was reestablished and everything had quieted down. There were just no people left in the area. There wasn’t a living breathing soul any where around.

Question: Because of your inferiority in numbers and strength, you did not make any attempt to recover weapons or to do any further checking out, is that correct?

L’Heureux: Yes sir, on the way back, we looked generally from the turret to see if there were any weapons there. We didn’t find any. At all

Question: Did you actually receive any fire throughout the whole engagement?

L’Heureux: Yes sir, I’d say we did. 25 or 30 rounds

Question: In that village?

Question: Did you actually receive any fire throughout the whole engagement?

L’Heureux: Yes sir, I’d say we did. 25 or 30 rounds

Question: In that village?

L’Heureux: Yes sir. When we first arrived in Vietnam, we debarked from the ship and we were taken into relief the old 3rd Battalion 9th Marines. That is 1st Battalion 9th Marines, to relieve them and took over the ONTOS firing position on the airstrip. As I remember, 2 companies on the airstrip, 2 ONTOS on the south end of the airstrip and one on the north end. On the south end of the airstrip, there was a bit of discussion about the employment. The Company Commander who was in charge down there wanted them deployed on the line and assign the primary direction of fire, just as he would employ his machine guns. Contrary to any advice that was given by myself and my ONTOS Company Commander. This was done for a while. They dug down in tank pits and stayed right shoulder to shoulder with infantry on the line, as I said, against all advice. On July 3rd, when the airfield was penetrated, it turned out the ONTOS was the only thing able to stay on the line and continue firing through out the fire, mostly muzzle flashes. No knowledge at all of any casualties. Major caliber weapons were not fired at all. After that more people were put around the airstrip and a regular watch was set up. At which time we’re able to talk the infantry Battalion into NOI’s to deploy. Another ONTOS which was made around the airstrip back about 100-150 yards from the wire itself and covered any area that there was decent field of fire and also be able to deploy somewhat within the confines of the wire barrier. One ONTOS was kept as a mobile force of some kind, on alert throughout the night as well as a Platoon tank. Major caliber weapons were never fired around the airstrip due to the number of civilians living in the areas adjacent to the airstrip. But it was felt strongly by everyone in ONTOS that they should not be used as a machine gun, which was the general consensus among the infantry at the time, although this attitude later changed. Several bad experiences due to this happened to Battalions in the field, 1st Battalion 1st Marines had an ONTOS destroyed one night because it was left on a line too long rather than kept to the rear of the main line itself, for some kind of flexibility, it kept on a skyline just standing right out there. It was destroyed by 57 mm fire. From that time on, to my knowledge, it was never done anymore. ONTOS was put on the line with infantry kept to the rear. The only other think I can think to discuss are supply problems, which were acute. Almost to the day we landed, before we deployed to Vietnam from Okinawa, were a pretty…well, there was a noticeable shortage of repair parts. At that time, something was wrong with the fan belt in the ONTOS. The order had to be made with special specifications, these had not yet arrived, we were using mighty mike fan belts at the rate of 3-4 a day to keep things running. All this took up quite a bit of time and maintenance caused a few personnel problems due to wearing the troops out on constant maintenance on the same thing. Also problems were had with the alternators. I’m not sure of the exact technical nature, but I know they were leaking, when the alternator starts leaking it didn’t work anymore, you lose the battery charge. All this had to be take care of. Generally the other problems are ones that could be expected…spark plugs. There were no spark plugs there. The only spark plugs in the Battalion were the ones I had to scrounge from ARVN, ARVN Personnel Carry unit who used the same engine. We later on got quite a few parts from them, traffic and spark plugs which were at a premium. I know for the motor transport I had attached to my platoon, spark plugs again were a problem. Although that was the only main problem, that I understand we had. The Army was very helpful when we first got there and offering us any additional help we could use on an unofficial basis. And later on, it wasn’t actually during the rainy season, it was before that it became noticeable that the tracks, when used long enough in the wet, mud and rice paddy would begin to rot. Although there was no outward indication, the track seemed firm enough. An ONTOS would be running along then lose 3 sections of track all in the same instance which would disable it. Each ONTOS normally carried one spare section of track. Another problem with the ONTOS, although the weight distribution relationship is outstanding, allowing it to traverse all that terrain, the track is extremely difficult to change since it requires a matching up of a number of small holes and use of a thing called a track ax which acts like a big pair of pliers, operated with a large bolt and takes sometimes 4 to 5 hours to….., I have troopers staying up all night to change a piece of track. I remember one afternoon, after an operation, the track was broken by a tree stump which a tree had been severed by a tank and the track hit this and broke. It took almost 4-5 hours which held a lot of troops in the field just to protect this one ONTOS while the track was being repaired. It just became extremely difficult. Another big problem was towing cables, there was not enough towing cables to go around. Each ONTOS should carry at least one towing cable and it should be better construction than the ones they had out there because they just separate generally around the plate and then many were old and the towing cables were not all the same length which would make it difficult to tow. All kinds of jury rigs arrangements had to be made if the towing cables weren’t the same length. Generally the track problems got pretty bad, a lot of tracks came in, tracks were used up constantly. Perhaps consideration ought to be given for development of a new type of track for the ONTOS. In spite of the fact that the tracks we have now are efficient they are extremely difficult to replace.

Question: What’s your overall evaluation of the ONTOS in the environment such as Vietnam?

L’Heureux: Tactically, sir, it lends a great deal of support to the infantry, although its drawbacks are mainly, the big drawback is the maintenance factor, which is tremendous in Vietnam and the back way, tactically is a big problem. You just have to work around it.

Question: Do you consider using the same vehicle but a different type of ordinance on in it, such as a machine gun or…?

L’Heureux: The weapons carrier itself is sound and the 106 concept, I think is sound although it has its drawbacks. I know that experiments have been made in Phu Bak in mounting 50 caliber machine guns in place of 106 rifles, but the experiments were discontinued for some reason. The only consideration that ought to be made to improve the weapon is perhaps arming it with the automatic M79 weapon which fires the 45mm grenade. I know they use it on helicopters. This would be an outstanding type of thing to have on there. I would like to see in place of the 30 caliber machine gun, a faster firing weapon, such as the M60 or, even though it doesn’t have faster firing it has more power, 50 caliber.

Question: Right, with the M60 machine gun you'd be able to exchange ammunition with any supporting infantry units you might have.

L’Heureux: Yes sir, it became our policy after this time to carry 5 boxes of ammunition in the ONTOS, purely to give to the supporting infantry. It was almost constantly used up once they found out we had it, they used it.

Question: Besides the M79 firing device possible the canister round or white phosphorous round for the 106 would be a tremendous improvement met in ordinance, is that correct? As previously mentioned? Alright, thank you.

L’Heureux: Yes sir, I believe so. The only after thought I’d be having would be the communications aspect. I think definitely the AM59 or PRC10, which is used to net with the infantry should be changed and the new PRC25 put in there with its much greater range and also particularly due to the fact that it has a lock on frequency. The PRC10 bought..a change is required, for instance, say from a Company tact net, which you’re supporting to a Battalion tact net, requires a new calibration and it’s just almost impossible to achieve in a moving vehicle and get anything at all also it’s just too darn fragile to be any good at all. RT66 and PP12 work pretty well but it’s very difficult to get aligned over there and due to the fact that they get bounced around quite a bit and knocked out of alignment almost immediately. So you wind up having little or no communication at any range whatsoever. Again, I’d like to repeat that I think of great used would be some type of tank infantry phone. Probably the best place to mount it would be on the flank on the ONTOS, far enough forward to keep the support infantry out of the back light and still close enough to use the phone throughout the firing.


My Vietnam Experience with an Ontos Unit

by Ralph Waring Beck

PFC Ralph Waring Beck, USMC Vietnam 1966

I was so eager to become a Marine that I quit high school with only about fourteen weeks to go before graduation and left for Marine Corps Recruit Depot, San Diego, California to begin my recruit training on 23 February 1965.  While in Receiving Barracks awaiting the formation of our Platoon, we were informed that the first combat troops, two Battalions from the 9th Marine Expeditionary Brigade, arrived in Vietnam just north of Da Nang on 8 March 1965.  I graduated Marine Corps Boot Camp on 20 May 1965 with the other recruits in Platoon 313 and began Infantry Training (ITR) with Company B, 1st Battalion, 2nd Infantry Training Regiment, Marine Corps Base Camp Pendleton, California on 23 May 1965.  I fully expected to become a “Grunt” (Infantryman) with an MOS (Military Occupational Specialty) of 0311; however, I was surprised to find that upon graduation from ITR I had been assigned an MOS of 0353 – Ontos Crewman.  I had no idea what an Ontos was, but it sounded better than “Grunt”.

On 30 June 1965, I reported to Company B, 1st Anti-Tank Battalion, 1st Marine Division, Camp Pendleton, California.  Two days later I took my “Boot Leave” and went home to Wisconsin for the next twenty days.  Upon returning from leave, I fully expected to begin formal training at Camp Delmar, California for Ontos Crewman School, but that was not to be.  On 3 August 1965 I was reassigned to Company A, 1st Anti-Tank Battalion, 1st Marine Division Reinforced, Fleet Marine Force, Camp Pendleton, California.  Just three days later we embarked aboard the USS Wexford County LST-1168 (Landing Ship Tank) at San Diego and headed for “Southeast Asia”. 

We were part of a four ship convoy that left San Diego, California – made a brief stop at Midway Island in the “middle” of the Pacific, where I celebrated my 18th birthday (14 August 1965).  We crossed the International Dateline on 16 August 1965 and continued our voyage.  When we got to Okinawa two of the ships in our convoy continued on to Vietnam, but the Wexford County, along with one other ship, docked at White Beach, Okinawa, Japan where we disembarked.  For the next ten weeks we underwent extensive “On the Job” (OJT) training with our Ontos.  I was trained as a Loader, but also learned how to drive and fire all the weapons on the Ontos, and had some basic instruction in vehicle maintenance.  We also completed the Counter Insurgency Guerrilla Warfare Training School at Jungle Lane, Northern Training Area.  We were based at Camp Hansen and spent our time off frequenting the whores and bars in and around Kin Village. 

On 7 November 1965 I was re-assigned to Headquarters & Service Company, 1st Battalion, 3rd Marine Regiment, 3rd Marine Division Reinforced, Fleet Marine Force, and on 10 November 1965, the 190th birthday of the Marine Corps, we embarked aboard the USS Oak Hill LSD-7 (Landing Ship Dock), headed for the South China Sea.  We floated around for the next week and rumors were rampant aboard ship.  We were going to Japan, or the Philippines, back to Okinawa, or on our way to Vietnam.  The issue was settled on 18 November 1965 when we disembarked at Red Beach, Da Nang, South Vietnam.  The previous day, three Battalions of Viet Cong and one Battalion of North Vietnamese military troops overran a South Vietnamese Army (ARVN) outpost at Hiep Duc.  The outpost overlooked Que Son Valley – a strategic area between Da Nang and Chu Lai.  Under attack, the ARVN abandoned their post and left behind a large supply of weapons and ammunition, now in enemy hands.  It was going to be our job to help retake the outpost.

The Ontos Commanders and Drivers stayed with the vehicles aboard the USS Oak Hill, while the Loaders went ashore with the Grunts by climbing down the rope ladders, into Amphibious Assault Landing Crafts (LCM-6) and hit the beach in a typical World War II beach assault.  However, there was no opposition to our landing.  The Ontos were offloaded at Da Nang, and we joined up with our vehicles in short order.  We traveled south along Highway 1 toward Hoi An, then Southwest toward Hiep Duc.  The sides of the roadway were lined with Vietnamese civilians who cheered and waved as we made our way into battle.  It was reminiscent of films I saw as a child of Allied Forces liberating cities and towns in Europe during World War II.

We were engaged in battle to retake the ARVN outpost at Hiep Duc within hours of arriving in Vietnam.  We were re-designated Company A, 3rd Anti-Tank Battalion Reinforced, 3rd Marine Division, Fleet Marine Force.  The Northeast monsoon season and weather conditions were at their worst.  In spite of the weather conditions, the battle was joined by Marine Air Group-11 (MAG-11) providing F-4B Phantom jets, and MAG-12 providing A-4 Skyhawks to conduct airstrikes in support of the operation.  MAG-16 and MAG-36 airlifted ARVN troops into the battle zone.  The Marine Infantry unit involved was the 3rd Battalion, 7th Marine Regiment (3/7) from Chu Lai.  Finally, two United States Destroyers, the USS O’Brien DD-725 and USS Bache DD-470 provided fire support from their locations at sea.  In the first six days of the battle enemy combatant losses were estimated to be 515 Killed In Action (KIA).

The enemy was routed from Hiep Duc, but remained strong in the area.  The Marines were kept on alert and ordered to conduct “Search and Destroy” operations while commanders planned a more detailed response.  The result was Operation Harvest Moon involving 2nd Battalion 7th Marine Regiment (2/7), 2nd Battalion 9th Marine Regiment (2/9), and 3rd Battalion 3rd Marine Regiment (3/3), reinforced with a Battery of 105mm Howitzers made up of elements of the 11th and 12th Marine Regiments. Also assigned to the operation were Tanks, Amtracs and Ontos, comprising the balance of the attack force, which was code named “Task Force Delta”.  Operation Harvest Moon was to be the largest combined operation of the war since the Marines arrived in Vietnam the previous March.  Starting on 12 December, the B-52 Stratofortress Bombers from the Air Force Base on Guam conducted bombing raids throughout the night and into the early morning hours of 13 December.  Operation Harvest Moon was officially ended on 20 December.  In addition to the 515 enemy KIA prior the start of Harvest Moon, the operation accounted for another 407 confirmed enemy KIA, 33 combatants captured and 60 tons of ammunitions and other supplies were confiscated.  Marine losses were 45 Marines KIA, 218 Wounded in Action (WIA).  ARVN losses were 90 KIA and 141 WIA.  Thus was my baptism under fire – a combined total of well over a thousand individuals on both sides losing their lives, and hundreds more wounded.

After Operation Harvest Moon we were relocated about 8 miles Northwest of the Da Nang Airbase at a little outpost named Le My.  It was known as an enemy stronghold and our main objective was to be a blocking force in an avenue that would protect the Da Nang Airbase from attack.  While there we had our share of daytime patrols and night ambushes.  The Ontos were set in the hills and repositioned almost every night to avoid enemy mortar rounds.  Frequently we would take incoming small arms fire from our North – on the opposite bank of the Ca De River.  On the evening of 22 January 1966, about twilight, the enemy launched an assault on Le My.  While standing in front of my Ontos, I was struck by a round that ricocheted off the vehicle, hitting me behind my left knee.  Just as I was hit my Ontos Commander, Staff Sergeant Gerald Ogle, or perhaps my Driver, Lance Corporal Jimmy Rutherford, pulled me to the ground, probably saving me from further injury.  My wound was slight, but it was a wake-up call for me. 

Our Ontos would rotate back to Company Headquarters every ten to fourteen days for maintenance.  Those trips were a welcome relief to the hard conditions we faced at Le My.  There we lived in canvas tents with overturned ammunition boxes to form the deck.  The monsoon weather turned the ground throughout the area, including inside our tents, to raging rivers.  The rats and centipedes made their homes in our racks, foot lockers, and wherever they could to escape the weather.  Showers and hot meals were rare.  In February 1966, after three months of very difficult duty, I had the opportunity to take a job in the Company Office as an Administrative Clerk.  Apparently typing was a rare skill, and that was enough to land me a new assignment.  From my new locale, I would frequently ride shotgun on vehicles taking ammunition, fuel, mail and other supplies to my old friends still in the field.  Those rides, while sometimes punctuated with sniper fire, were much safer than being assigned to an Ontos Crew out in the sticks.  However, one particular ride became the most memorable of my life.

Trying to find a “shortcut” to our destination, three of us were in a jeep carrying mail.  Our weapons were holstered or on the deck of the jeep.  The “road” turned into a trail, and then almost disappeared into the jungle.  We were putt-putting along at just a couple miles per hour on some awfully rough terrain making a wide turn to the right, when out of the jungle stepped three Vietcong, their weapons at the ready.  They stood frozen just a few feet to our left, and our eyes locked as we slowly drove past them.  The tallest of the three, standing in the center, was carrying a Browning Automatic Rifle (BAR).  He let us get about fifteen yards past them, and he let loose with a burst of eight to ten rounds just over our heads, and let out a huge laugh that seemed way out of proportion for his size.  We just kept inching along and somehow made it back to our outpost.  I have been haunted by this experience ever since it occurred.  I just cannot understand why he and his comrades didn’t just kill us on the spot.  They would have had our jeep, uniforms, weapons, radios, and the supplies we were carrying, and we were completely helpless to defend ourselves.  What bothers me the most is that I believe if the situation had been reversed, I would not have been so compassionate.  I would have taken their lives with little or no hesitation.  Over the years, I have often prayed for the salvation of that enemy soldier, so one day I could meet him in heaven and thank him for sparing the life of a stupid kid Marine, and my friends.

I was due to rotate back to the United States in September 1966, and received orders to report to the 5th Marine Division at Camp Pendleton, California.  Having more than two years to go on my enlistment, I was sure that I would spend a short time at Pendleton, and would soon find myself back in Vietnam for another tour of duty.  Therefore, I decided to extend my current tour by 90 days in exchange for any duty station “East of the Mississippi River”.  My extension was approved and I settled in for the next three months working in the company office.

What I didn’t know was our entire Company was about to move North to the area around the Demilitarized Zone (DMZ).  In August 1966 Operation Prairie began to establish and maintain a blocking force along the southern edge of the DMZ to prevent the North Vietnamese Army (NVA) from crossing the DMZ at will.  Since every Marine is first and foremost an infantryman, my new job as administrative clerk did little to keep me out of danger.  We traveled north along Highway 1 to Dong Ha, then West along Highway 9 and finally settled at Camp J. J. Carroll.  On the way we encountered double and triple canopy jungle, but when we arrived at Camp Carroll it was as barren as the landscape of the moon.  We had dumped enough Agent Orange and other toxins on the land to kill everything that grew.  My last three months in Vietnam were similar to my first three.  Cold, wet, tired, hungry, enjoying the monsoons along with the smell of gun powder and napalm.  Operation Prairie ended with more than 100 Marines KIA, 200 WIA and 1300 enemy KIA.  Fortunately, I was spared much of the action of that operation, as it covered such a large geographical area and I was involved for less than half the time it was taking place.  Nevertheless, I was more than ready to see 18 December 1966 come around and my return home.

The last two years of my active duty enlistment were spent at Marine Air Reserve Training Detachment, Marine Air Reserve Training Command, Naval Air Station, Grosse Ile, Michigan.  I continued in my job as Administrative Clerk and trained Marine Reservists as my primary assignment.  There were only about ninety active duty Marines on the base.  Other duty included providing military funeral honors for Marines KIA whose home of record was in and around Detroit, Michigan.  I went on countless funerals, and in some cases, the duty was worse than serving in Vietnam.  I was frequently overtaken by guilt, as I lay to rest fellow Marines who paid the ultimate price for all of us to enjoy “life as usual” back in “The World”.

During the years that followed my service in Vietnam I have made four humanitarian missionary trips back to Vietnam, two of them with my wife, Lynn.  I have helped in the construction of three medical clinics and one children’s playground on those trips.  I also revisited all the areas where I served as a young Marine.  I have found my purpose in life doing volunteer work helping veterans, their families and supporting their causes.  In Vietnam I made friends that have lasted a lifetime, and remember those who became causalities of war.  To this day I am friends with our Company Corpsman, Ric “Doc” Gardiner, and a few others that I count among my blessings: Rick Murdie, Pat “Frenchy” Canulette, Gary “Lightening” Hartman, John “Pi-man” Paiva, Dana Hunter, John “Sergeant” Williams, and Steve Valdez.  I have had brief encounters with others and would like to build deeper friendships with them: Elwood “Woody” Carpenter, Robert “Bob” Becker, David “Dave” Stegmeier, and Daniel “Danny” Welch.  Whenever I am able to visit The Wall I pause to remember some of those we left behind: Greg Weaver – KIA 26 May 1966, Robert “Bob” Gage – Missing In Action (MIA) 3 July 1966 (body not recovered), Raul Orta – KIA 1 February 1967, Philip Sauer – KIA 24 April 1967, Wayne Hayes – KIA 6 July 1967 and some 17 others that served with Ontos units that were KIA sometime during my tour from November 1965 to December 1966.

M-50A1 Ontos Le                                                                                My Outpost, Viet Nam 1966

Company A, 3d Anti-Tank Battalion, 3d Marine Division



By Michael Scudder

How the project found me.

It all started innocently enough, I read an article on the Ontos in a military vehicle magazine. The article reminded me of my contacts with the Ontos while serving as a Marine infantryman. I thought it was great that the Marine Corps had adopted a hot rod tank (OK anti tank). It was fast, quick turning and had the best exhaust tone of anything in our era. It also had more fire power from its six 106 mm recoilless rifles than the main battle tanks. The Ontos crews were known to bring ammo, water, food and mail when the needs arose. The little tank was always a welcome sight.

My reading of the Ontos article coincided with seeing Jack Tomlin’s ad for an Ontos chassis along with pallets of parts. I began to wonder how difficult it would be to build an upper hull for the chassis and end up with an Ontos look-a-like. I was soon to be retired and I needed a good project. This was to be a great project.

I then had a conversation with Bill Watson of Greensboro, NC about buying one of his restored M274 mules. In a “by the way” conversation, I asked Bill his opinion about the building of an upper hull on the Ontos chassis. Bill then laid the bombshell on me. He said he had a running Ontos chassis in the chicken house on his father’s old farmstead. He said the chassis had been converted into a test boring machine. Bill had swapped a mule for the machine. He enjoyed taking the kids for rides in it.

It was more than 6 months later when my wife and I traveled from Houston, Texas to Greensboro, NC to pick up the mule. I was focused on seeing Bill’s running Ontos chassis. After meeting Bill and completing the purchase of the mule, I got directions to the farm and chicken house. There it was…..covered in dust, chicken feathers and chicken s…….. (droppings). Most of my memories of military service are of Chicken s……. (droppings). It was a match made in heaven.

Bill also told me about some parts Ontos at White Owl Military Parts in Kinston, NC. White Owl had purchased some Ontos chassis that had been converted into fire buggies for the transport of fireman and equipment for the forest service. He suggested that I call a former Marine who traveled to White Owl often. Maybe he might take some photos of what may be available.

A call to White Owl’s Jerry Hill revealed: 1. Yes, the yard had several Ontos chassis in an overgrown section of the yard. 2. No, he could not take photos of them as it would take too much tree cutting to even find them much less photograph them. 3. If I wanted more information, I should travel to White Owl and look for myself. I did.

Next I called the former Marine, Gunny Sergeant David Macgillivary of Jacksonville, NC. This old salt was well known in military vehicle circles for putting his military vehicles in the movies. I asked him if he would take some photos of the Ontos hulls for me.

Gunny Dave did travel to White Owl and took a photo of the only Ontos chassis that was not buried in the overgrowth. It was missing the rear 2/3 of the hull and turret. It had a 2” diameter tree growing in the gunner’s area. Based on the photo, I booked air fare to NC.

Dave and I agreed to meet at White Owl. I rented a car and bought a machete at a local hardware. Dave brought bush cutters. It was a perfect day for two retired guys to play Tarzan in the woods: 90 degrees, 90 % humidity, and not a breeze within two states. We spent 4 hours just finding the seven Ontos chassis and cutting away enough brush to get a photo of one side. Three of the chassis had some part of the sloping front armor left intact. It wasn’t much, but it was more parts than I had hoped for. The iron had been in the yard for about 12 years. White Owl wanted to clean up this part of the yard, so I was able to purchase all seven Ontos for a sale price. Sale is my word and not one my wife may have used.

I returned to Texas to decide how many chassis I should attempt to haul home. I also needed a brain damaged 18 wheeler driver that would take his rig into Bill Watson’s fields to get the chicken house chassis. I concluded I could only haul 4 chassis. The remaining four would be inflicted on Gunny Dave who suffered from the Ontos virus also.

A neighbor had used the services of “Freddy the trucker” to maneuver his large rig into hay fields. He was what I was looking for: skilled, fearless and brain damaged from years of country dancing in Baptist county. Freddy had been a bull rider and rodeo clown and he had as many old stories as I had old jokes. We would spend six days in his old truck picking up three chassis from White Owl and one from Bill Watson.

Loading the three chassis from White Owl was an ordeal for everyone involved. The weather had managed to get even hotter than on my first visit. One of my chassis was

in a swampy section of the yard and the clutch-challenged folk lift refused to perform. Everyone was nearing heat exhaustion when a trusty 5 ton truck utilized its front winch to extract the last chassis without any strain. The folks at White Owl were great people to deal with and they made me feel at home.

The next morning found Freddy and me nearing Bill Watson’s farm. Bill had arranged a small crane to lift the chicken house chassis onto the 18 wheeler. Bill and I had guessed the chassis to weigh about 6,000 pounds. The crane was chosen based on this guess. We guessed wrong-real wrong. The Ontos got 3” off the ground when the lift stalled. The operator made a more educated guess at 11,000 pounds and a new selection of lifting equipment was ordered.

The selection of an off-loading crane in Texas was done with considerably more knowledge than guesswork. I arrived in my pasture after six days of transport with 42,000 pounds of rusted junk: none of which looked like an Ontos. A small crowd of neighbors, who were observing the off loading, were now discussing my mental stability.

The Ontos chassis were off loaded from the trailer into 25 acres of cow pasture adjacent to my house and shop. The chicken house Ontos was to be the basis of the first project. I pulled the Ontos towards my shop using my 40 HP farm tractor. It could pull it in a straight line as long was no steering brakes were applied. Turns were affected by pulling on a corner of the machine until it pivoted in the new direction. I got the chassis within a few yards of the shop and exchanged the electric fuel pump. The engine came to life and, after taking the bark off a nearby oak tree, the machine was driven into the shop.

I had a running chassis in the shop. The second non-running chassis had been a fire buggy but not run in 12 years. This machine was left in the pasture near enough to the shop to act as a parts donor should the need arise. The engine had been exposed to the weather. The two other machines were without tracks and missing suspension parts, but these hulls had the sloping front armor and many spare parts.

My biggest challenge on this project is one that many of the readers are familiar - rust. The machines had been in poor storage for years and few bolts could be removed. The 2” diameter tree that had grown in my main donor machine had its roots threaded throughout the ammo locker. I would later get a turret on a parts exchange from a military museum. Only the casting survived the years. Even those parts made from plate iron were unsalvageable. That is the reason rebuilders are loved by plate and machine shops. I performed all the plate work, but the machine shop and a sheet metal shop did some damage to my bank account.

I removed about 1,000 pounds of the non-military steel body that had been overlaid on the armored bottom hull. The floor had large torch cut holes and the rear ammo door was cut out by torch. After sand blasting, painting and parts swapping, I laid the front armor on the bottom chassis. It may not have looked like an Ontos yet, but it was starting to look military.

At this same time Gunny Dave had located a supply of decommissioned 106mm recoilless rifles in Bedford, Indiana. We purchased 12 rifles and four M8 .50 caliber spotting rifles. Dave transported the rifles on his flat-bed trailer. There was no concern that the purchase could be identified as former weapons. The load looked like a load of old oil drill pipe. The guns were torch cut in half with about 2” removed. The breaches, muzzles and chambers had torch cuts. The spotting rifles were cut in half through the barrels and receivers. The cut barrels still had packing paper in them. These barrels had never been fired. The building of parade guns from these parts was straight forward.

I mocked up the missing rear hull plates with 1/2” plywood which then acted as patterns for the steel fabrication. The two rear doors were cut by measurement as a single door. After the doors were finished fabricated and hung on hand built hinges, I cut the doors into two pieces by torch. This simplified the door alignment. These doors have a horizontal bend at the bottom 1/3. This bend was duplicated by sitting the doors over two timbers while I used a friend’s 19,000 pound dozer to apply the bending force through the dozer’s blade. I have since learned that this technique is common in this part of Texas.

As you may understand, the original 12 gage fenders had a wrinkle or two. I found the best way to straighten them was to clamp them to a steel I beam and pound them straight with progressively smaller hammers, starting with a sledgehammer and ending with a body man’s bumping hammer.

The turret was a study in rust. I used every technique known to man to include: sand and shot blasting, hammering, needle descalers, wire brushing, water blasting. It took two days of hand work to get the gunner’s hatch to open and close. In the end it looked fine - from 20 feet away. I had to fabricate those parts that were on the outside of the turret including the steel straps that hold the gun to the turret’s revolving arms.

The original rubber bladder gas tank was removed and replaced with a standard 5 gal. jeep can converted to act like a boat’s fuel tank (with small rubber pump bulb). The can is mounted on the outside of the vehicle in a spot where a water or oil can was often mounted. The can has a quick disconnect fitting and seems to function well. The gas can then be removed when the vehicle is to be shown inside a public building. I will replace the gas can for a water can while being shown.

I am nearing the end of this seven year rebuild. There were many periods of little or no activity-little or no money, but the project has been great and brought me in contact with many former Ontosmen who I consider friends.

Where? Here’s a Few Clues

By the end of 1967 the Ontos were reaching the end of their sustainability on the battle field. The 2 Ontos Battalions ceased to exist; the Ontos were consolidated into a single reinforced antitank company and placed, one each, into a tank battalion for administrative and most operational control.

A year later, the Marines deactivated their Ontos units and the vehicles were handed over to the Army’s light infantry brigade. The Army used them until their parts ran out and then employed them as bunkers. What happened to them after that is largely unknown.

Ironically, excess Ontos were given to Army forces (recall that the Army initially rejected the Ontos as being unsuitable for its requirements). These Army Ontos went to Company D, 16th Armor, 173rd Airborne Brigade. The Army used its Ontos until they ran out of spare parts; then employed them in fixed bunkers.

After Vietnam, some were handed over to civilian agencies and used as forestry vehicles. A tiny number made it into collectors’ hands. Some are in museums. According to Mike Scudder, a former Marine who owns several, there are more World War I tanks in circulation than there are Ontos. This may not actually be true, since “there are believed to be more than 60 Ontos sitting discarded in the desert on a Marine Corps reservation near China Lake, Calif. If they are still there, no one is saying.” (Brendan McNally’s 12Feb13 article M50 Ontos: The Forgotten Tank-killer)

Upon return to the United States, the tops of the vehicles were removed. Many of the chassis were sold for use as construction equipment or give to local governments for rescue work. One “platoon” of surplus M50s wound up in the service of the North Carolina Forestry Service for use as fire fighting vehicles. According to Vietnam veteran and former Ontos Marine Mike Scudder, Ontos today are scarce. Scudder should know: he bought seven rusty sections from North Carolina and is restoring two of them. More than 60 Ontos are believed to be stored in the desert at the Marine Corps facility, Naval Air Warfare Center, China Lake, CA. (From article written by Peter Brush)

John Williams: I know that some Ontos were sold to the South Carolina Dept. of Forestry.  They were used on the fire line to transport men and firefighting materials to areas that could not be reached by rubber tired vehicles.  After this use they were sold for scrap.

Jim Renforth: Rumor has it, some of the boys from "Duck Dynasty" may have (perhaps) picked up a few of them to use as ready-made 'duck blinds'. Purely rumor, mind you, and the accuracy of this may well justify a site visit or two (or more). But, geez - who knows for sure?

Bob Peavey: Many Ontos were bought by the Land Bureau and had cages welded around them. The large number of Ontos were given, believe it or not, to the U.S. Army when we left Vietnam. There were two units that received them, I used to know the unit designations but forgot. I'll see if I can find it again.

D.C. Satcher: “Ugly ONTOS is Underrated”, Nov 1969: “…. The last one (in Vietnam) was removed to Okinawa.

Brendan McNally: “M50 Ontos: The Forgotten Tank-killer”, Feb 2013: “A year later (1969), the Marines deactivated their Ontos units and the vehicles were handed over to the Army’s light infantry brigade. The Army used them until their parts ran out and then employed them as bunkers. What happened to them after that is largely unknown.

Mike Scudder: I can confirm that about 50 Ontos are now at the China Lake Naval Range. The Camp Pendleton's Museum of Transportation received three Ontos, three years ago, that had known combat histories from China Lake. It took much political pull to have the Navy release them and it is doubtful any more will leave the base. Jerry Cook is the main force in getting these released.  He acts as a volunteer at the museum. Since writing my paper on my rebuilding, I made a swap with the museum and got a more complete turret that had seen action at Hue City. Rick States of NY/Long Island has collected four or more chassis and a damaged but almost complete Ontos that had escaped from China Lake many years ago. Rick is a great collector, but I know of no wrench turning being done with the exception of an engine rebuild. Rick has set up a museum in a building in Up State NY. I have sold, and have attempted to mentor a young man from Greenville, TX, a lower chassis and parts machine with some frontal armor. It is my hope that he can do what I have done with C22. It requires the hand making of many parts.

MUSEUM OF THE MARINES, Jacksonville, NC contact Sgt Maj Houle.  This was one of the chassis I gave Gunny Dave Macgilvary.  He got it running and the Sgt Major had the Camp Lejeune hobby shop do much work on it.  It ran, but had no interior when I saw it last. 

AMERICAN MILITARY MUSEUM, S. El Monte, CA.  This Ontos is pretty complete less guns.

ROCK ISLAND ARSENAL MUSEUM, Rock Island, Il.  This is a prototype Ontos and differs in many details from the production Ontos. 

MCB 29 PALMS has a static display Ontos on the north side of the road into the base. 

PATTON MUSEUM Ontos is owned by the Army and in good storage at Ft Benning and sometimes used as a teaching tool for young Army officers.  It will be moved to Washington, DC when the Army builds its National Museum. 

NATIONAL MUSEUM OF THE MARINE CORPS The Ontos has been gutted of its running gear and interior.  It was restored by Air Force volunteers.  It has the wrong shade of paint. .

MUSEUM OF THE FORGOTTEN WARRIOR, 5865 A  Road, Marysville, CA.   The museum has plastic pipe representing the guns.  The website shows an interesting collection.  Don Schrader said he would open the museum if after hours at 530-682-0674

MUSEUM OF THE AMERICAN GI  College Station, Texas.  Brent Mullins is finishing an A+ restoration of an Ontos received from Jerry Cook at the Camp Pendleton Museum.  It should be finished during the first few months of 2016

A PDF photo article of surviving Ontos