M113 APC: four decades of service and still showing potential

Infantry Magazine, July-August, 2004 by Stanley C. Crist

The first version of the M113 armored personnel carrier (APC) was introduced in 1960. Operated by a driver and track commander (TC), it was designed to transport a squad of 11 infantrymen across a hostile battlefield. To maximize strategic and tactical mobility, the M113 was made to be air-transportable, air-droppable, and swimmable, thereby enabling it to be employed in a wide range of combat scenarios.

In 1964 the original 209 horsepower (HP) gasoline engine was replaced by a more fuel-efficient 212 HP diesel package, which increased cruising range by 50 percent. Since diesel fuel is less flammable than gasoline, this change also improved crew survivability. This version--the M113A1--was the primary ground combat vehicle used by American, Australian, and South Vietnamese threes in the Vietnam War.

The suspension and cooling system were upgraded in 1979, resulting in the M113A2. This variant was employed in the 1989 invasion of Panama, during Operation Just Cause, where it was a valuable asset to U.S. infantrymen. Large numbers of the A2 also participated in Operation Desert Storm, albeit in support roles, as combat duty in that 1991 action was the province of the M2 Bradley fighting vehicle.

Because the M113A2 had difficulty keeping pace with the Abrams tank and Bradley fighting vehicle, in 1987 the M113A3 was created. A 275 HP turbocharged engine increased top speed by more than 10 percent, producing cross-country performance that is officially considered comparable to the Abrams and Bradley. To enhance survivability of both men and machine, spall liners were installed and the single internal fuel tank was replaced by dual armored tanks mounted externally on the rear of the vehicle.

In a quest for even better performance, in 2002 the Australian Army initiated a program to "stretch" the M113 hull approximately three feet, adding another mad wheel on each side. Together with increased suspension travel and a 350 HP diesel engine, these modifications give the Australian M113AS4 APC tactical mobility equal to, if not better than, the Bradley fighting vehicle. A similar long wheel base M113 variant was evaluated by the U.S. Army in the interim armored vehicle program, but was passed over in favor of the eight-wheel drive Stryker.

COUNTERINSURGENCY OPERATIONS--VIETNAM

When the United States provided M113 APCs to the Army of the Republic of Vietnam (ARVN) in 1962, American advisors tried to instill into the Vietnamese the official U.S. Army doctrine of employing the M113 only as a "battle taxi." During a September 1962 attack against guerrilla forces in the Plain of Reeds, the U.S. advisor convinced the ARVN Commander to have the infantry dismount and fight on font. The troops immediately became bogged down in the knee-deep water, enabling the enemy to inflict an alarming number of casualties.

To the consternation of the higher echelons of rite American command, the ARVN refused to continue this practice, correctly reasoning that the troops were far more mobile and better protected when in the APC than when slogging through rice paddies with only a fatigue shirt between their bodies and the enemy's bullets. lit an effort to further improve combat effectiveness and Soldier survivability, the ARVN soon took another step to increase vehicle firepower and crew protection.

As issued, the M113 was armed with as single M2 HB .50 caliber machine gun, mounted out in the open Oil the front of the commander's cupola, thereby exposing the TC to enemy fire. As a result of having 14 out of 17 track commanders killed in the 1963 battle of Ap Bac, the Vietnamese fabricated steel armor shields that were attached in front of the "fifty" on the APCs. They also installed an additional .30 caliber Browning machine gun with armor shield on each side of the cargo hatch. Thus was born the armored cavalry assault vehicle, or ACAV, a weapon system that was called "the champion VC killer of I Corps" by Colonel R. R. Battreall, an advisor to the South Vietnamese in 1965.

An improved version of tire ACAV was fielded by the 11th Armored Cavalry Regiment when it deployed to Vietnam in 1966, and other American mechanized units also had their M113s equipped with armor shields and extra machine guns. According to General Donn Starry, in his 1989 book, Mounted Combat in Vietnam (accessible online at www.army.mil/cmh-pg/books/Vietnam/mounted/index.htm), "more often than not U.S. mechanized infantry fought mounted, employing armored personnel carriers as assault vehicles to close with and destroy the enemy, and that mounted troops generally suffered fewer and less serious casualties than toot Soldiers."

The ACAV concept proved exceedingly effective on the nonlinear battlefield of Southeast Asia, even though the insurgents were well armed with RPG-2 and RPG-7 rocket launchers, as well as a variety of recoilless rifles. Despite this fact, after United States threes withdrew from South Vietnam, the gunshields and 7.62mm machine guns were removed from U.S. Army ACAVs, restoring the vehicles to prewar configuration. Consequently, when M113s were next employed in combat, during Operation Just Cause, track commanders were once again vulnerable to small arms fire. Fortunately, because the operation was brief and the opposition was ineffective, U.S. casualties were minimal.