The M1 Abrams Main Battle Tank (MBT) is the namesake of the late General Creighton W. Abrams, former Army Chief of Staff and commander of the 37th Armored Battalion. It is the backbone of the armored forces of the United States military, and several of US allies as well. The purpose of this vehicle is to provide mobile firepower for armored formations of sufficient capability to successfully close with and destroy any opposing armored fighting vehicle in the world, while providing protection for it's crew in any conceivable combat environment. It is capable of engaging the enemy in any weather, day or night on the multi-dimensional, non-linear battlefield using its firepower, manuever, and shock effect. The Abrams Tank System synchronizes its high tempo, distributed manuever via its digitized situational awareness and the fusion of onboard and remote battlefield sensors.

Production of M1A1 tanks for the US Army is complete. Over 8,800 M1 and M1A1 tanks have been produced for the US Army and Marine Corps, and the armies of Egypt, Saudi Arabia and Kuwait. Production of new M1A1 and M1A2 Abrams tanks is in its final phase for Foreign Military Sales. Three versions of the Abrams tank are currently in service the original M1 model, dating from the early 1980s, and two newer versions, designated M1A1 and M1A2. The M1A1 series, produced from 1985 through 1993, replaced the M1's 105mm main gun with a 120mm gun and incorporated numerous other enhancements, including an improved suspension, a new turret, increased armor protection, and a nuclear-chemical-biological protection system. The newer M1A2 series includes all of the M1A1 features plus a commander's independent thermal viewer, an independent commander's weapon station, position navigation equipment, and a digital data bus and radio interface unit providing a common picture among M1A2s on the battlefield.

In lieu of new production, the Army is upgrading approximately 1,000 older M1 tanks to the M1A2 configuration. The Army also initiated a modification program for the M1A2 to enhance its digital command and control capabilities and to add the second generation forward looking infrared (FLIR) sights to improve the tank's fightability and lethality during limited visibility. This system enhancement program will be fielded in the 2000 time frame concurrently with the M2A3 Bradley and other advanced digital systems. The initial M1A2 fielding to the First Calvary Division, Ft. Hood, TX, is underway. The Army will continue to field M1A2s to the CONUS contingency corps and other first to fight units into the next decade.

The M1 series tank is equipped with a 1500 horsepower Lycoming Textron gas turbine engine coupled to an Allison hydrokenetic transmission with four forward and two reverse gears. It's tactical crusing range is approximately 275 miles. Despite it's weight, the M1 can attain a top speed of nearly 45 miles per hour. The main armament is a 120mm smooth bore cannon, which replaced the 105mm gun on the initial M1 version. It has day/night fire on the move capability which is provided by a laser range finder, thermal imaging night sight, optical day sight, and a digital ballistic computer. Both the fuel and ammunition are compartmented to enhance survivability. The hull and turret are protected by advanced armor similar to the Chobam armor developed by the British Ministry of Defense. When required, the Abrams may be fitted with "reactive armor" to thwart armor-defeating munitions.

Although fielded in 1980, the Abrams remained untested for over 10 years. When Iraq invaded Kuwait in August 1990, there were concerns that the Abrams would fall victim to the sand and long months of continuous operation without the luxury of peacetime maintenance facilities. There were also doubts about the combat survivability of the extensive turret electronics. Immediately following President Bush's decision to commit US forces to the Gulf region in defense of Kuwait and Saudi Arabia, American armored units began the difficult process of relocating to the threatened area. Due to the shear size and weight of the Abrams, the C-5 Galaxy, the largest cargo aircraft in the US Air Force inventory, was only able to handle one tank at a time. This meant that nearly all of the Abrams tanks deployed in the Gulf War were shipped by cargo ship. Although slow in coming, the arrival of the Abrams was much welcomed by Allied forces, as it is capable of defeating any tank in the Iraqi inventory.

The Iraqi Army had a considerable array of tanks, mostly purchased from the former Soviet Union. Chief among these were about 500 T-72's. These modern Soviet tanks were armed with an excellent 125mm smoothbore weapon and had many of the same advanced features found on the Abrams. Despite it's advanced design, the T-72 proved to be inferior to the M1A1's deployed during the Gulf War, and compared more closely with the older M60A3 tanks used there by the US Marine Corps. In addition, Iraq had a number of earlier Soviet models: perhaps as many as 1,600 T-62 and about 700 T-54, both of which were developed in the 1960's. These tanks were widely regarded as clearly inferior to the Abrams, but were expected to be highly reliable mechanically. The Gulf War provided military tacticians with an opportunity to evaluate developments in tank design that had not been available since World War II.

In his book "Desert Victory - The War for Kuwait", author Norman Friedman writes that "The U.S. Army in Saudi Arabia probably had about 1,900 M1A1 tanks. Its ability to fire reliably when moving at speed over rough ground (because of the stabilized gun mount) gave it a capability that proved valuable in the Gulf. The Abrams tank also has. vision devices that proved effective not only at night, but also in the dust and smoke of Kuwaiti daytime. On average, an Abrams outranged an Iraqi tank by about 1,000 meters." The actual numbers of Abrams M1 and M1A1 tanks deployed to the Gulf War (according to official DOD sources) are as follows: A total of 1,848 M1A1 and M1A1 "Heavy Armor" (or HA) tanks were deployed between the US Army and Marine Corp (who fielded 16 M1A1's and 60 M1A1(HA) tanks).

As the Gulf War shifted pace from Operation Desert Shield to Operation Desert Storm, and the preparatory bombardment lifted, U.S. Abrams tanks spearheaded the attack on Iraqi fortifications and engaged enemy tanks whenever and wherever possible. Just as they had done in the Iran-Iraq War, the Iraqi Army used it's tanks as fixed anti-tank and artillery pieces, digging them into the ground to reduce target signature. However, this also prevented their quick movement and Allied air power smashed nearly 50% of Iraq's tank threat before Allied armor had moved across the border. After that the Abrams tanks quickly destroyed a number of Iraqi tanks that did manage to go mobile.

The Abrams' thermal sights were unhampered by the clouds of thick black smoke over the battlefield that were the result of burning Kuwaiti oil wells. In fact many Gunners relied on their "night" sights in full daylight. Such was not the case with the sights in the Iraqi tanks, which were being hit from units they could not even see. Concerns about the M1A1's range were eliminated by a massive resupply operation that will be studied for years as a model of tactical efficiency.

During the Gulf War only 18 Abrams tanks were taken out of service due to battle damage: nine were permanent losses, and another nine suffered repairable damage, mostly from mines. Not a single Abrams crewman was lost in the conflict. There were few reports of mechanical failure. US armor commanders maintained an unprecedented 90% operational readiness for their Abrams Main Battle Tanks.

M1A1

The M1A1 is an improved version of the M1 Main Battle Tank (MBT). It includes a 120mm smoothbore main gun, an NBC overpressure protection system, and an improved armor package. This tank significantly increases the capabilities of the Fleet Marine Forces across the full spectrum of conflict in the near and midterm. The M1A1 Tank, in addition to the improved armor, 120mm smoothbore gun and the NBC overpressure system, has a Deep Water Fording Kit (DWFK), a Position Location Reporting Systems (PLRS), enhanced ship tiedowns, Digital Electronic Control Unit (DECU) (which allows significant fuel savings),and Battlefield Override.

The main weapon of the M1A1 is the M256 120mm smoothbore cannon, designed by the Rheinmetall Corporation of Germany. Engagement ranges approaching 4000 meters were successfully demonstrated during Operation Desert Storm. The primary armor-defeating ammunition of this weapon is the armor-piercing, fin-stabilized, discarding sabot (APDS-FS) round, which features a depleted uranium penetrators. Depleted uranium has density two and a half times greater than steel and provides high penetration characteristics. Several other types of ammunition are available as well. It is reliable, deadly accurate and has a "hit/kill ratio" that equals or surpasses any main battle tank armament in the world.

As with virtually every tank every fielded by the US, the familiar .50 caliber Browning M2 Heavy Barrel machine gun - the "Ma Duce" - is located in a powered mount at the Commander's station and is equipped with a x3 magnification sight. The Loader is provided with a 7.62mm M240 machine gun, and another M240 is mounted in-line with the main gun of the tank ("coaxially"). It is in a fixed mount and is aimed with the main gun to suppress enemy ground troops.

The layout of the Abrams follows classic tank design and accommodates a crew of four: Commander, Gunner, Loader and Driver. The Commander and Gunner are seated on the right side of the turret. The Loader is seated on the left side of the turret, and the Driver is seated at the center front of the hull.

The Commander's station is equipped with six periscopes which provide all round 360 degree view. The Independent Thermal Viewer (ITV) from Texas Instruments provides him with independent, stabilized day and night vision with a 360 degree view, automatic sector scanning, automatic target cueing of the Gunner's sight with no need for verbal communication, and a complete back-up fire control system - the Commander is capable of firing the main gun independent of the Gunner.

The Gunner's Primary Sight-Line of Sight (GPS-LOS), was developed by the Electro-Optical Systems Division of Hughes Aircraft Company. The night vision Thermal Imaging System (TIS), also from Hughes, creates an image based on the differences of heat radiated by objects in the field of view. The thermal image is displayed in the eyepiece of the Gunner's sight together with the range measurement to within 10 meters of accuracy, from a Hughes laser range finder, which is integrated into all of the fire control systems. The Abrams also has an onboard digital fire control computer. Range data from the laser rangefinder is transferred directly to the fire control computer, which automatically calculates the fire control solution. The data includes 1) the lead angle measurement, 2) the bend of the gun measured by the muzzle reference system of the main armament, 3) wind velocity measurement from a wind sensor on the roof of the turret and 4) the data from a pendulum static cant sensor located at the center of the turret roof. The Gunner or Commander manually inputs the data on the ammunition type and temperature, and the barometric pressure and the weapon is prepared for engagement.

The Loader's station is located on the left side of the turret and has no special fire control equipment.

The Driver's station is located at the center front of the hull. The Driver is in a semi-reclined position when his hatch is closed, as it must be whenever the vehicle is in operation. His station is equipped with a standard array of gages and monitors reflecting the condition of vehicle fluid levels, batteries and electrical equipment. The Driver has either three observation periscopes or two periscopes on either side and a central image intensifying ("Starlight") periscope for night vision. The periscopes provide 120 degrees field of view. The Driver's night vision equipment enables the tank to maneuver at normal daytime driving speeds in darkness and in poor visibility conditions such as in the dust and smoke encountered on the battlefield.

The turret is fitted with two six-barreled M250 smoke grenade launchers, one on each side of the main gun. The standard smoke grenade contains a phosphors compound that masks thermal signature of the vehicle to the enemy. A smoke screen can also be laid by an engine operated system.

An improvement program will eventually upgrade all M1A1 tanks with steel encased depleted uranium armor, which has a density at least two-and-a-half times greater than steel. The depleted uranium armor will raise the total weight of the Abrams tank to 65 tons, but offers vastly improved protection in the bargain.

The stowage for the main armament ammunition is in armored ammunition boxes behind sliding armor doors. Armor bulkheads separate the crew compartment from the fuel tanks. The tank is equipped with an automatic Halon fire extinguishing system. This system automatically activates within 2 milliseconds of either a flash or a fire within the various compartments of the vehicle. The top panels of the tank are designed to blow outwards in the event of penetration by a HEAT projectile.

Nuclear, Biological and Chemical (NBC) warfare protection is provided by an overpressure clean-air conditioning air system, a radiological warning system, and a chemical agent detector. The crew are individually equipped with protective suits and masks.

The Marine Corps has fielded the M1A1 Common Tank to replace the aging M60A1 Rise/Passive tank. The M60 has reached the end of its service life and lacks the capability to survive and to defeat the threats expected to be encountered on the modern battlefield. During Operation Desert Shield/Storm, the Marine Corps borrowed 60 M1A1s (called the M1A1 Heavy Armor) from the US Army. There were also 16 Marine Corps M1A1 Tanks delivered on an accelerated schedule for employment during the operation. This total of 76 M1A1 tanks was employed by 2d Tank Battalion and elements of 4th Tank Battalion. The M1A1 tanks saw immediate action during the I Marine Expeditionary Force (IMEF) drive through the burning Kuwaiti oil fields. All loaned tanks were returned to the US Army after Desert Storm.

Due to unique Marine Corps amphibious requirements, and the need for both supportability and interoperability between the Marine Corps and the US Army, the two services agreed to jointly produce the M1A1 Main Battle Tank. The M1A1 MBT has the capability to conduct operations ashore. It is compatible with all US Navy amphibious ships and craft (to include the LCAC) and Maritime Prepositioning Ships (MPS). The USMC completed fielding of all tanks, to include active, reserve, MPS, and depot maintenance float (DMF) during FY 96.

In 1995 the 26th MEU became the first amphibiously deployed unit to carry the M1A1. This added some complication to the logistics of the unit due to the tank's weight. Topping the scales at over 68 tons the vehicle requires special care during amphibious operations. One tank can be carried at a time on an Air Cushioned Landing Craft (LCAC), two on a Landing Craft Utility (LCU), but only during fairly calm seas. For operations with the Marine Corps, tanks have been equipped with special fording systems. These modifications include extended air intake and exhaust tubes that allow the vehicles to cross rivers and shallow waters such as the surf zones that Marines operate in.

The M1A1 Abrams Tank Firepower Enhancement Program (FEP), a Marine Corps Systems Command initiative, is intended to increase the all weather, day and night target acquisition and engagement ranges and provide a far target location capability for the M1A1 Tank. The FEP system will include a scope of work that entails a suite of upgrades for the M1A1 Tank. These upgrades include a second-generation thermal sight and a north finding/target locating capability. The system will increase the tank crew's ability to detect, recognize, identify and accurately locate targets.

M1A1D Abrams Main Battle Tank

The M1A1 fleet remains the majority of the Armor Force. The M1A1D is a digitized M1A1 that provides improved situational awareness and far target designate capability. The installation of a digital appliqué command and control package on the M1A1 is necessary to achieve Force XXI required capabilities. Another planned improvement is replacing the analog Turret Network Box (TNB) and Hull Network Box (HNB) with new digital units to eliminate the associated obsolescence problems and to allow the introduction of a built-in-test (BIT) capability to support the Force XXI maintenance structure. Digital TNBs and HNBs also allow future electronic growth by providing unpopulated VME card slots.

In the survivability area the Army is working to develop and field a contingency armor package that is thin and lightweight, but with a high level of protection. These armor packages can be applied to either the side or front of Abrams tanks to provide additional protection as required by the mission. The Army is also seeking to fundo resource upgrades to the M1A1 fire control system with the same 2nd Gen FLIR package on the M1A2.