The M109 was designed to serve as a mobile artillery system that could provide firesupport for US ground forces. This weapon system was first used during the Vietnam conflict, and has been used by the U.S. and many of its allies since the 1960s. Over a dozen different variations of this dependable vehicle have been developed over the years, and the "Paladin" variant continues to serve as the main support artillery for U.S. mobile forces.

The A2 version of the M-109 featured dozens of improvements to the vehicle's reliability, making it easier to maintain and reducing the amount of maintenance required to keep it functioning. It also sported the longer-barreled M185 155mm gun, with improved targeting systems and a larger ammunition supply.