After the helicopter demonstrated its early battlefield capabilities in the Korean War, the United States Army began experimenting with expanded roles and missions for them. This culminated in 1962 with the formation of the Tactical Mobility Requirements Board, which strongly recommended the adaptation of helicopters in a variety of roles and missions. In 1963, the 11th Air Assault Division was activated to test a number of the Board's concepts and recommendations about air mobility. Because the 155mm howitzers then assigned to Army divisions as medium support artillery were not transportable by helicopters, the concept of aerial rocket artillery (ARA) was developed as a substitute.Tolson, p. 23.Stanton, Shelby. Anatomy of a Division. Presidio, 1987. p. 203. The original test unit for rocket-armed helicopters within the 11th Air Assault Division was the 2nd Battalion, 42nd Artillery (later designated the 3rd Battalion, 377th Artillery). When the 11th Air Assault was redesignated as the 1st Cavalry Division and sent to Vietnam, the 3/377th became the 2nd Battalion, 20th Artillery (using the radio call sign "Blue Max").Stanton, p. 28; 258. This was the first unit designated and organized as ARA to take part in combat operations. The 4/77th Artillery joined the 101st Airborne Division in 1969 when the 101st was converted to an airmobile division, becoming the second active ARA battalion. Battery F, 79th Artillery, was formed to serve with the separate 3d Brigade of the 1st Cavalry Division when the rest of the division was withdrawn from Vietnam. It was the final ARA unit to see combat service.
