The M113 is a fully tracked armored personnel carrier currently manufactured by BAE Systems. The vehicle was first fielded by United States Army's mechanized infantry units in Vietnam in April 1962. The M113 was the most widely used armored vehicle of the U.S. Army in the Vietnam War, earning the nickname 'Green Dragon' by some people, but largely known as an APC and ACAV (armored cavalry assault vehicle) by the allied forces, as it was used to break through heavy thickets in the midst of the jungle to attack and overrun enemy positions.

 

The M113 introduced new aluminum armor that made the vehicle much lighter than earlier vehicles; it was thick enough to protect the crew and passengers against small arms fire but light enough that the vehicle was air transportable and moderately amphibious. In the U.S. Army, the M113 series have long been replaced as front-line combat vehicles by the M2 and M3 Bradley, but large numbers are still used in support roles such as armored ambulance, mortar carrier, engineer vehicle, command vehicle, etc. The Army's Heavy Brigade Combat Teams are currently equipped with around 6,000 M113s and 4,000 Bradleys.

 

The M113's versatility spawned a wide variety of adaptations that live on worldwide, and in U.S. service. These variants together represent about half of U.S. Army armored vehicles today. To date, it is estimated that over 80,000 M113s of all types have been produced and used by over 50 countries worldwide, making it one of the most widely used armored fighting vehicles of all time. The Military Channel's "Top Ten" series named the M113 the most significant infantry vehicle in history. The U.S. Army plans to retire the M113 family of vehicles by 2018 and is seeking replacement with the GCV Infantry Fighting Vehicle program.

 

History

Development

Origins

 

FMC T113 proposal

 

FMC T117 proposal

 

The M113 was developed by Food Machinery Corp. (FMC), which had produced the earlier M59 and M75 Armored personnel carriers. The M113 bore a very strong resemblance to both of these earlier vehicles. The M75 was too heavy and expensive to be useful; its weight prevented amphibious capability, and being transported by air. The lightened M59 addressed both of these problems, but ended up with too little armor, and was unreliable as a result of efforts to reduce its cost.

 

The Army was looking for a vehicle that combined the best features of both designs, the "Airborne Armored Multi-Purpose Vehicle Family" (AAM-PVF).[7] of all-purpose, all-terrain armored fighting vehicles FMC had been working with Kaiser Aluminum and Chemical Co. in the late 1950s to develop a suitable aluminum armor. Use of this armor could produce a vehicle that provided the protection of the M75, and the light weight and mobility of the M59.

 

FMC responded with two proposals; two versions of the aluminum T113 - a thicker and a thinner armored one - along with the similar but mostly steel T117. The thicker-armored version of the T113, effectively the prototype of the M113, was chosen because it weighed less than the steel competitor, while offering the same level of protection. An improved T113 design, the T113E1, was adopted by the U.S. Army in 1960 as the M113. A diesel prototype T113E2 was put into production in 1964 as the M113A1, and quickly supplanted the gasoline-engined M113. In 1994, FMC transferred the M113's production over to its newly formed defense subsidiary, United Defense. Then in 2005, United Defense was acquired by BAE Systems.

 

U.S. Army soldiers dismount from an M113 armored personnel carrier during a training exercise in September 1985.

 

The M113 was developed to provide a survivable and reliable light tracked vehicle able to be air-lifted and air-dropped, by C-130 and C-141 transport planes. The original concept was that the vehicle would be used solely for transportation, bringing the troops forward under armor and then having them dismount for combat; the M113 would then retreat to the rear. Entering service with the U.S. Army in 1960, the M113 required only two crewmen, a driver and a commander, and carried 11 passengers inside the vehicle. Its main armament was a single .50-caliber (12.7 mm) M2 Browning machine gun operated by the commander.

 

On 30 March 1962, the first batch of 32 M113s arrived in Vietnam, and were sent to two Army of the Republic of Vietnam (ARVN) mechanized rifle companies, each equipped with 15 of the APCs (M113s). On 11 June 1962, the two mechanized units were fielded for the first time. During the Battle of Ap Bac in January 1963, at least fourteen of the exposed .50 caliber gunners aboard the M113s were killed in action, necessitating modifications to improve crew survivability. Soon, makeshift shields formed from metal salvaged from the hull(s) of sunken ships were fitted to the carriers, which afforded better protection. But, finding that this material could be penetrated by small arms fire, subsequent shields were constructed from scrapped armored vehicles.

 

The ARVN 80th Ordnance Unit in South Vietnam developed the shield idea further and commenced engineering general issue gun shields for the M113. These shields became the predecessor to the standardized Armored Cavalry Assault Vehicle (or ACAV) variant and were issued to all ARVN mechanized units during the early 1960s. The ARVNs had modified the M113s to function as "amphibious light tanks" and not as battle taxis as US designers had intended. Instead of an armored personnel carrier, the ARVN used the carried infantry as extra "dismountable soldiers" in "an over-sized tank crew." These "ACAV" sets were eventually adapted to U.S. Army M113s with the arrival of the Army's conventional forces in 1965. The vehicles continued to operate in the role of a light tank and reconnaissance vehicle, and did not operate as designed in theater. Still, the M113 could carry 11 infantrymen inside, with two crewmen operating the M113.

 

Interior of an M113 at the American Armored Foundation Museum in Danville, Virginia, July 2006.

 

The U.S. Army, after berating the Vietnamese for flouting battle doctrine, came out with their own ACAV version. This more or less standardized ACAV kit included shields and a circular turret for the .50-caliber M2 machine gun in the Track Commander (TC) position, two M60 machine guns with shields for the left and right rear positions, and "belly armor" - steel armor bolted from the front bottom extending 1/2 to 2/3 of the way towards the bottom rear of the M113. The two rear machine gunners could fire their weapons while standing inside the rectangular open cargo hatch. This transformed the M113 into a fighting vehicle, but the vehicle still suffered from its lightly armored configuration, having never been designed for such a role.

 

In order to improve the fighting ability of the mounted troops, a number of experiments were carried out in the 1960s under MICV-65 project, which aimed to develop a true "infantry fighting vehicle" rather than an "armored personnel carrier". Pacific Car and Foundry entered the steel-armored XM701, but this proved to be too slow and too heavy to be airmobile, even in the C-141. FMC entered the XM734, which was largely the ACAV M113, but whereas the M113 seated the troops facing inward on benches along the walls, the XM734 sat them facing outwards on a central bench. Four gun ports and vision blocks were added on each side to allow the seated troops to fire even while under cover. Although neither the XM701 or XM734 were deemed worthwhile to produce, FMC continued development of their version as the XM765 Advanced Infantry Fighting Vehicle (AIFV). The AIFV was sold to a number of third party-users in the 1970s, including the Netherlands, the Philippines and Belgium.

 

Modifications

 

United States Air Force M113 at the Theater Internment Facility at Camp Bucca, Iraq, Feb 10, 2008.
 

The vehicle is assigned to the 886th Expeditionary Security Forces Squadron's quick response force and equipped with M5 Crowd Control Munitions.
 

Modified versions of the Vietnam War ACAV sets have been deployed to Iraq (formerly referred to as Southwest Asia within the US military) to equip the standard M113s still in service. The circular .50 caliber gun shields have been modified, however the rear port and starboard gun stations have been deleted for service in that region. Some of these modified vehicles have been utilized for convoy escort duties.

 

The M113 has relatively light armor, but it can be augmented with add-on steel plates for improved ballistic protection. Also, reactive armor and slat armor can be added for protection against RPGs. Windowed gunshields developed by an armorer in Iraq are reminiscent of ACAV vehicle modifications so effective in Southeast Asia (Vietnam War).
Band tracks are in use by Canadian and other forces to enable stealthy operation, less damage to paved roads, and less vibration and rolling resistance.

 

Most of the 13,000 M113s which are still in U.S. Army service have been upgraded to the A3 variant.

 

The M113 has also been adopted to replace the aging fleet of visually modified (vismod) M551s being used to simulate Russian-made combat vehicles at the U.S. Army's National Training Center in Fort Irwin, California. These M113s, like the M551s they replaced, have also been modified to resemble enemy tanks and APCs, such as the T-80 and BMP-2. One of the advantages of the M113 being used to simulate the latter is that the infantry squad can now ride inside the simulated BMP instead of in a truck accompanying a tank masquerading as one, as was often the case with the M551s.

 

Combat history
 

Vietnam

 

A combined arms operation in Vietnam. M113s clear the way through heavy bush while infantry follows.

 

The Vietnam War was the first combat opportunity for "mechanized" infantry, a technically new type of infantry with its roots in the armored infantry of World War II, now using the M113 Armored Personnel Carrier. In addition, Armored Cavalry squadrons in Vietnam consisted largely of M113s, after replacing the intended M114 in a variety of roles, and Armor battalions contained M113s within their headquarters companies, such as the maintenance section, medical section, vehicle recovery section, mortar section, and the scout (reconnaissance) section. U.S. Army mechanized infantry units in Vietnam were fully equipped with the M113 APC/ACAV, which consisted of one headquarters company and three line companies, normally with an authorized strength of approximately 900 men. Ten U.S. mechanized infantry battalions and one mechanized brigade were deployed to Vietnam from 1965 until their departure in 1972.

 

ACAVs of the 3rd Squadron 11th Armored Cavalry assume a herringbone formation during Operation Cedar Falls.
 

This formation gave vehicles optimal all-round firepower in the event of an ambush in a restricted area.
 

M113s were instrumental in conducting Reconnaissance In Force (RIFs), Search and Destroy missions, and large invasions (incursions) such as during the U.S. invasion of Cambodia on 1 May 1970 and later Laos (Operation Lam Son 719) in 1971; all of which used the M113 as the primary work horse for moving the ground armies. While operating with Cavalry and Armor units, the M113s often worked in conjunction with U.S. M48 Patton and M551 Sheridan tanks. During the Vietnam War, U.S. Army gun trucks (modified 2½-ton and 5-ton cargo trucks), along with V-100 armored cars, conducted convoy escorts for military traffic.

 

The USAF used M113 and M113A1 ACAV vehicles in USAF Security Police Squadrons, which provided air base ground defense support in Vietnam. M113s were also supplied to the South Vietnamese Army of the Republic of Vietnam (ARVN). One notable ARVN unit equipped with the M113 APC, the 3d Armored Cavalry Squadron, earned the Presidential Unit Citation.[16][17] M113s were also supplied to the Cambodian Khmer National Armed Forces, equipped with a turret for the machine gun and a recoilless rifle mounted on the roof.

 

The Australian Army also used the M113 in Vietnam. After initial experience showed the crew commander was too vulnerable to fire, the Australians tried a number of different guns shields and turrets, eventually standardizing with the Cadillac-Cage T-50 turret fitted with two .30 cal Browning machine guns, or a single .30/single .50 combination.
Other turrets were tried as were various gun shields, the main design of which was similar to the gun shield used on the U.S. M113 ACAV version.

 

In addition, the Australians operated an M113 variant fitted with a Saladin armored car turret, with a 76 mm gun as a fire support vehicle, or FSV, for infantry fire support. This has now also been removed from service.

 

Subsequent to Vietnam all Australian M113 troop carriers were fitted with the T50 turret. The FSV was eventually phased out and replaced with a modernized version known as the MRV (medium reconnaissance vehicle). The MRV featured a Scorpion turret with 76 mm gun, improved fire control, and passive night vision equipment.

 

Law enforcement

M113s have been adopted by some law enforcement agencies. Photos show an M113 marked "Midland County Sheriff" was used in the 2008 raid of the Fundamentalist Church of Jesus Christ of Latter Day Saints compound. The Osceola County Sheriff also uses one for their S.W.A.T Team.

 

Brazilian Marine Corps's M113s have been used in joint operations with Batalhão de Operações Policiais Especiais during the raid to Complexo do Alemão

 

Recent history

 

 

In March 2007, a group of U.S. Army soldiers sit on the rear ramp of an M113, staging for a reconnaissance mission in Forward Operating Base Kalsu, Iraq.

 

Today’s M113 fleet includes a mix of M113A2 and A3 variants and other derivatives equipped with the most recent RISE (Reliability Improvements for Selected Equipment) package. The standard RISE package includes an upgraded propulsion system (turbocharged engine and new transmission), greatly improved driver controls (new power brakes and conventional steering controls), external fuel tanks, and 200-amp alternator with four batteries. Additional A3 improvements include incorporation of spall liners and provisions for mounting external armor.

 

The future M113A3 fleet will include a number of vehicles that will have high speed digital networks and data transfer systems. The M113A3 digitization program includes applying appliqué hardware, software, and installation kits and hosting them in the M113 FOV.

 

Nicknames

The M113 has received a variety of nicknames over the years. The South Vietnamese Army (ARVN) called it the "Green Dragon".

 

U.S. troops tended to refer to the M113 simply as a "track" or an ACAV. The IDF employs the M113 in many different variants, all designed in Israel, and has given each of them official names, from the baseline "Bardelas" over the "Nagmash", "Nagman", and "Kasman" variants for urban combat up to the "Zelda" and "Zelda 2", which were fitted with ERA armor-suites. The Australian Army refers to its M113A1s as "Buckets", "Bush taxis" and the modified M113A1 fitted with 76 mm turrets as "Beasts". The German Army has various nicknames, depending on location and branch of service, including "Elephantshoe", "Tank Wedge" and "Bathtub".

 

While some claim the M113 has been nicknamed "Gavin" (after General James M. Gavin), this is not an official designation. One observer said "I have never, never heard anybody use the name “Gavin” for the M113. Not in the US nor in any of the many countries that use the vehicle. Not in the military forces, not in the companies that build and equip it, not in the groups that retrofit and repair it."

 

Replacement

It was the U.S Army's intention that the BCT Ground Combat Vehicle Program replace the M113 by 2018 with the GCV Infantry Fighting Vehicle meanwhile displacing the other vehicles into task specific roles of the M113. Vehicles displaced into specific roles of the M113 are then to be replaced entirely by future variants of the GCV.

 

The M113 will now be replaced by the Armored Multi-Purpose Vehicle (AMPV) program.

 

Design

Armament

 

Australian M113A1 with athe Cadillac Gage T50 turret fitted with twin mounted M1919 Browning and M2 Browning QCB machine guns.
 

The basic M113 armored personnel carrier can itself be fitted with a number of weapon systems. The most common weapon fit is a single .50 caliber M2 machine gun. However, the mount can also be fitted with a 40 mm Mk 19 automatic grenade launcher. A number of anti-tank weapons could be fitted to the standard variant: the U.S. Army developed kits that allowed the M47 Dragon and BGM-71 TOW anti-tank missile systems to be mounted. In the case of the M47, the system mated to the existing machine gun mount, without having to remove the machine gun. This allowed the commander to use the weapon, as well as the machine gun. A large array of turrets and fixed mounts are available to mount high explosive cannon from 20 mm to 105 mm to the M113 series making them function also as assault guns and fire support means; while in many cases still having room inside to carry dismounted infantry or cavalry scouts.

 

Armor

The 10.5-ton M113 is built of 5083 aircraft-quality aluminum alloy which gives it some of the same strength as steel at a slightly reduced weight, as the greater thickness allows structural stiffness.

 

Mobility

Its weight allows the use of a relatively small engine to power the vehicle, a 6V53 Detroit 2-stroke six cylinder diesel, with an Allison tx100-1 3 speed automatic transmission, and allows the vehicle to carry a large payload cross-country and to be transported by fixed- and rotary-wing aircraft. The M113 can swim without deploying flotation curtains, and is propelled in the water by its tracks.

 

Basic variants

 

APC by David E. Graves, Vietnam Combat Artists Program, CAT IX, 1969-70. Courtesy of National Museum of the U.S. Army.
 

M113

Original version, powered by 209 hp (156 kW) Chrysler 75M V8 petrol engine.

 

M113A1

Starting in 1964, the gasoline engine was replaced with a 215 hp (160 kW) diesel engine, to take advantage of the better fuel economy and reduced fire hazard of the diesel engine. The suffix A1 was used on all variants to denote a diesel engine, i.e. an M106A1 was an M106 mortar carrier equipped with a diesel engine.

 

M113A2

In 1979 further upgrades were introduced, including cooling and suspension improvements and smoke grenade launchers on the glacis plate. The suffix A2 is used on all variants to denote upgrade to A2 standard.

 

M113A3

In 1987, further improvements for "enhanced (battlefield) survival" were introduced. This included a yoke for steering instead of laterals, a more powerful engine, external fuel tanks and internal spall liners for improved protection. The suffix A3 is used on all variants to denote upgrade to A3 standard.

 

M113 Armored Cavalry Assault Vehicle (ACAV) variant

 

M113 ACAV in Vietnam, 1966

 

The "Armored Cavalry Assault Vehicle" or "ACAV", was a concept and field modification pioneered by the South Vietnamese Army (ARVN) in 1963 during the Vietnam war.
ARVN troops utilized the M113 armored personnel carrier as an infantry fighting vehicle, and more often than not, as a light tank by fighting mounted rather than as a "battle taxi" as dictated by U.S. Army doctrine.

 

After it was found that the commander and cargo hatch positions were extremely exposed and the commander and troops hence vulnerable to enemy fire, the South Vietnamese engineers thought out a simple and cheap remedy to this problem: Initially field expedient shields and mounts were made from sunken ships, but this was soft metal and could be penetrated by small arms fire. Finally armor plate, from scrapped armored vehicles was used; this worked well, and by the end of 1964 all ARVN ACAVs were equipped with gun shields. For the US Army, ACAV sets were produced industrially in Okinawa for the .50 cal. machine gun, and rear aft and starboard M60 machine gun positions. Finally, the ARVN's ACAV modifications were adopted by the US Army in Vietnam, and by 1965 the full ACAV set was mass-produced in the U.S. The kit included shields and circular turret armor for the commander's M2 .50 caliber machine gun, and two additional 7.62 mm M60 machine guns, again with shields, fitted on either side of the top cargo hatch. This kit could be retrofitted to any M113. ACAV sets were sometimes fitted to the M106 mortar carrier, but the different rear hatch found on this vehicle required the left M60 machine gun to be fitted to the extreme rear instead of the side. Many kits were added in the field, but at least in the case of the 11th Armored Cavalry Regiment, the vehicles had their ACAV sets installed in the U.S. prior to their deployment to Vietnam in 1966 from Ft. Meade, Maryland. Additional armor in the form of a mine protective kit under the hull was also frequently fitted.