M113 armored personnel carrier
The M113 is a fully tracked armored personnel carrier that was developed and produced by the FMC Corporation. The M113 was sent to United States Army Europe in 1961 to replace the mechanized infantry's M59 APCs. The M113 was first used in combat in April 1962 after the United States provided the South Vietnamese army with heavy weaponry such as the M113, under the Military Assistance Command, Vietnam program. Eventually, the M113 was the most widely used armored vehicle of the U.S. Army in the Vietnam War and was used to break through heavy thickets in the midst of the jungle to attack and overrun enemy positions. It was largely known as an "APC" or an "ACAV" by the allied forces.
The M113 was the first aluminum hull combat vehicle to be put into mass production. Much lighter than earlier similar vehicles, its aluminum armor was designed to be 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 Bradleys, but large numbers are still used in support roles such as armored ambulance, mortar carrier, engineer vehicle, and command vehicle. The U.S. Army's heavy brigade combat teams are equipped with approximately 6,000 M113s and 6,724 Bradleys.
The M113's versatility spawned a wide variety of adaptations that live on worldwide and in U.S. service. These variants together currently represent about half of U.S. Army armored vehicles. It is estimated that over 80,000 vehicles in the M113 family have been produced and used by over 50 countries worldwide, making it one of the most widely used armored fighting vehicles of all time.
M113 production was terminated in 2007. The Army initiated the Armored Multi-Purpose Vehicle program to search for a replacement. In 2014, the U.S. Army selected BAE Systems' proposal of a turretless variant of the Bradley Fighting Vehicle to replace over 2,800 M113s in service.
Thousands of M113s continue to see combat service in the Israel Defense Forces, although by 2014 the IDF was seeking to gradually replace many of its 6,000 M113s with the Namers, and with the Eitan AFV in 2020.
Development
The M113 was developed by the FMC Corporation, which had produced the earlier M75 and M59 armored personnel carriers. The M113 bears a very strong resemblance to both of these earlier vehicles. The M75 was too heavy and expensive to be useful, as its weight precluded amphibious use and transport by air. The much cheaper and lightened M59 addressed both of these problems, but ended up with too little armor, and was unreliable as a result of its dual engine powertrain.The Army was looking for a vehicle that combined the best features of both designs, the "airborne armored multi-purpose vehicle family" of all-purpose, all-terrain armored fighting vehicles. FMC had been working with the Kaiser Aluminum in the late 1950s to develop a suitable aluminum armor that provided the protection of the M75 and the low weight and mobility of the M59.
FMC responded with two proposals; two versions of the aluminum T113 – one thicker and one more thinly armored – 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 its steel competitor, whilst 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. FMC transferred the M113's production in 1994 to United Defense, its newly formed defense subsidiary. United Defense was acquired by BAE Systems in 2005.
File:US Army infantrymen unload from an M113, 1985.jpg|thumb|U.S. Army soldiers dismount from an M113 during a mechanized infantry 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 to move the troops forward under the protection of armor and then having them dismount for combat, after which the M113 would retreat to the rear. Entering service with the U.S. Army in 1960, the M113 required two crewmen, a driver and a commander, and carried 11-15 passengers inside the vehicle. Its main armament was a single.50-caliber M2 Browning machine gun operated by the commander. The first batch of 32 M113s arrived in South Vietnam on 30 March 1962 and were sent to two Army of the Republic of Vietnam mechanized rifle companies, each equipped with 15 of the APCs.
The two mechanized units were fielded for the first time on 11 June 1962. During the Battle of Ap Bac in January 1963, at least fourteen of the gunners aboard the M113s were killed in action due to their exposed position, necessitating modifications to improve crew survivability. Makeshift shields formed from metal salvaged from the hulls of sunken ships were soon fitted to the carriers, affording better protection; however, it was found that this material could be penetrated by small arms fire, so 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 variant and were issued to all ARVN mechanized units during the early 1960s.
According to Ralph Zumbro the ARVN had modified the M113s to function as "amphibious light tanks" and not as the battle taxis U.S. designers had intended. Instead of an armored personnel carrier, the ARVN used the carried infantry as extra "dismountable soldiers" in "an oversized 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 not as designed in theater.
The U.S. Army soon 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 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. Canada also adopted the ACAV kits when employing the M113A2 during peacekeeping operations in the Balkans in the 1990s.
In order to improve the fighting ability of the mounted troops, a number of experiments were carried out in the 1960s under the MICV-65 project. These attempted 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 Lockheed C-141 Starlifter. FMC entered the XM734, which was largely the ACAV M113 but with the troops sitting facing outwards on a central bench, rather than facing inwards as in the M113. 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. The AIFV was sold to a number of third party-users in the 1970s, including the Netherlands, the Philippines and Belgium.
Modifications
Modified versions of the Vietnam War ACAV sets were deployed to Iraq to equip the standard M113s still in service. The circular.50 caliber gun shields have been modified, while 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 light armor, but it can be augmented with add-on steel plates for improved ballistic protection. Reactive armor and slat armor can be added for protection against rocket-propelled grenades. Band tracks made of rubber are in use by Canadian and other forces to enable stealthy operation, less damage to paved roads, higher speed, less maintenance, access to terrain where operation of wheeled vehicles is impractical and less vibration and rolling resistance.
Most of the 13,000 M113s that are still in U.S. Army service have been upgraded to the A3 variant. The current U.S. Army M113 fleet includes a mix of M113A2 and A3 variants and other derivatives equipped with the most recent RISE package. The standard RISE package includes an upgraded propulsion system, greatly improved driver controls, external fuel tanks, and 200-amp alternator with four batteries. Additional A3 improvements include the incorporation of spall liners and provision for mounting external armor.
The U.S. Army's National Training Center in Fort Irwin, California began replacing their aging fleet of visually modified M551s being used to simulate Russian-made combat vehicles with M113s in 1995. The Combat Maneuver Training Center near Hohenfels, Germany followed suit soon after, adopting the M113 to their M60A3s. 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. Besides being significantly cheaper and easier to maintain, one of the advantages of the M113 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.