First introduced in the early 1960s, the M109 155mm self-propelled howitzer has been updated numerous times – most recently to the M109A7. The M109 family of weapons is the most common indirect-fire support weapon of maneuver brigades and armored or mechanized infantry divisions in the Western world.

The M109 howitzer was developed as the medium-sized variant based on an United States program that adapted a common chassis for its self-propelled artillery units. It saw its combat debut during the Vietnam War. Since then, it has been used in conflicts such as the 1973 Yom Kippur War, the Lebanon Wars, the Iran-Iraq War, and the Gulf War. The M109 howitzer has seen many upgrades throughout its time, including upgrades to the cannon, ammunition, fire control, survivability, and electronics system.

As it was originally completed, the M109 was a conventional SPA form according to modern standards. It is fitted with a powerpack at its front-right and the driver is located in the forward hull located in the front-left. The turret was placed over the rear section of the vehicle with a large main gun located in the forward panel. A cupola was affixed to the commander’s position to which a 0.50 to 0.30-caliber machine gun was capable of being installed for local or air defense. This self-propelled howitzer was placed atop a track-and-wheel arrangement that included seven double-tired road wheels on each hull side. A small door, located at the rear of the hull, as well as side panels, roof hatches, and a driver’s compartment hatch, allowed for crew entry and exit. The main guns featured massive muzzle brakes and were attached to the hull when traveling. The necessary operating crew for the M109 is six – driver, commander, two gunners, and two loaders.

The variants for the M109 howitzer include:

• M109A1 and M109A1B

• M109A2

• M109A3 and M109A3B

• M109A4

• M109A5

• M109A5+

• M109A6 “Paladin”

• M109 “KAWEST”

• M109L52

• M109A3GNM

• K55/K55A1

• M109A7