C-22 was an M109 self-propelled 155mm howitzer built by the Allison Division of General Motors in 1967. It entered the U.S. Army inventory on 6 Jan 1968, was received at Letterkenny Army Depot on 16 Feb 1968, and was shipped to Vietnam on 1 May 1968. Issued to the 6th FA BN, 1st Inf Div, on 22 June 1968, it served at Fire Support Base Rita in the Fish Hook area in RVN. On the night of 28 Oct 1968, during a heavy barrage of recoilless rifle and rocket propelled grenade fire, C-22 was hit by an RPG round, causing damage to its left side. Four days later, it was instrumental in repelling a heavy ground attack by a North Vietnamese Sapper Battalion supported by intense rocket and mortar barrages. During that action, LTC Charles C. Rogers earned the Medal of Honor. In the battle, U.S. forces suffered 12 men killed and 54 wounded, while the enemy body count inside and on the perimeter wire was 27, with at least 200 bodies estimated to be lying in the woods around the fire support base. C-22 remained with the 6th FA BN until 13 Nov 1968, when it was retired and shipped to Tooele Army Depot, Utah. It was shipped to Fort Sill on 11 Jan 1972 and became the property of the Field Artillery Museum.