Staff Writer (Updated: 8/27/2015):
In February of 1981, the US Army set forth a requirement for a new tactical four-wheel drive light vehicle to take on the designation of High Mobility Multi-Purpose Wheeled Vehicle (HMMWV) and be capable of delivery to any given location on the battlefield via helicopter. The Army had found a tremendous amount of success with its World War 2-era series of small jeeps but the vehicle was still a design with its roots dug well into another time. Beyond that, it had experimented by militarizing civilian trucks for the same role but these conversions left much to be desired. As such, the HMMWV specification called for a universal solution to the Army's needs, one that would also peak interest from the United States Air Force and the United States Marine Corps equally. A multi-role product with commonality of parts and ease of conversion to other roles was now the call of the day. US Army requirements were high - perhaps a bit too ambitious - but the need was quite desperate.
By July of that year, the US Army had invited AM General, Chrysler Defense and Teledyne Continental to a prototype face-off, each required to build no fewer than eleven vehicles utilizing a common chassis but with conversions showcasing the type's possible multi-faceted use in the field. Prototypes would include a TOW-capable system, an unarmored base vehicle and a hardtop battlefield ambulance. The program was known as the XM998. Testing began in April of 1982 with AM General's design winning out.
Interestingly enough, AM General owed its origins to the Willys-Overland Company responsible for the World War 2-era "Jeep". Willys-Overland was purchased by Kaiser in 1953, becoming Kaiser-Jeep Corporation before indirectly evolving into AM General Corporation. American Motors Corporation purchased Kaiser-Jeep in 1970 and branched AM General as a subsidiary. Jeep Corporation now remained as a separate entity. During all this time, the companies were still fulfilling US Army needs and production of military trucks was their forte. Eventually, AM General was purchased out once again, this time by LTV Corporation in 1983. By 2004, AM General was now brought under ownership of the Renco Group.
AM General submitted a conventional four-wheel drive system with a forward-mounted diesel engine mated to an automatic transmission, a large passenger cabin and good off-road capabilities. AM General secured the Army's favor in their new system following the agreement of a $1.2 billion dollar contract on March 22nd, 1983, calling for the production and delivery of 55,000 total HMMWV examples. Additional USAF, USN and USMC orders brought the total closer to 70,000 examples.
The HMMWV development was sped along in order to enforce the ranks of the US Army. As such, the system appeared with some notable deficiencies when put through the rigors of military use. Maintenance for early HMMWVs proved a bear for Army mechanics and inherent reliability of these early vehicles left much to be desired. As such, efforts were made in part by the General Accounting Office to curtail the massive production contract awarded to AM General. The US Senate did just that on June 14th, 1984, which essentially forced the US Army to place the HMMWV design into further testing and evaluation. AM General managed to address several major and minor issues during this time and testing by the US Army, US Navy and US Marine Corps all helped to solidify the HMMWV as ready for production. The HMMWV entered service with the US Army in 1985.
The HMMWV was first fielded in anger in the 1989 US Invasion of Panama during Operation Just Cause (the operation also signified the introduction of Lockheed's F-117 Nighthawk stealth fighter) in an effort to unseat dictator Manuel Noriega. Operational results for the type proved excellent as a whole, showcasing reliability and good performance under the rigors of wartime use.
The HMMWV eventually took on the A0, A1 and A2 generational designations (A0 appeared retroactively after A1 was beginning its usage in US Army terminology). A0 represented the original production Humvees, these fitted with a 6.2 liter, 150 horsepower, liquid-cooled V-8 diesel engines. The engines were mated to a General Motors THM400 automatic transmission system featuring all-wheel drive capability. In all, the A0 family of variants comprised of the M998, M1038, M1037, M1042, M996, M997, M1035, M966, M1036, M1045, M1046, M1025, M1026, M1043 and M1044. A heavy-duty version of the A0 soon appeared in September of 1992 as the M1097 HHV (Heavy Hummer Variant). This new vehicle provided for an improvement to capabilities over the original A0 model thus expanding the products reach.
The A1 appeared in 1994 with revised front seats, grille and rifle mounts and was essentially developed from the M1097 HHV. These vehicles took on the designation of M998A1. The A1 family was comprised of the M998A1, M1038A1, M1097A1, M996A1, M997A1, M1035A1, M966A1, M1045A1, M1025A1, M1026A1, M1043A1 and the M1044A1.
The A2 was another much-improved Humvee with origins in the M998A1. A new 160 horsepower, 6.5 liter diesel engine was mated to a digital four-speed automatic transmission. Rear seats were redesigned as was the heater and steering column. A2's also had provision for the CTIS (Central Tire Inflation System) to be added as an option in the field. This on-the-fly adjustability provided for direct operator control in maneuvering the Humvee through the most unforgiving off-road terrain imaginable. The A2 variant line is made up of the M1097A2 (three versions of this model - base, mover and shelter carrier), M1123A2, M997A2, M1035A2, M1025A2, M1043A2 and the M1045A2.