The United States Army Aviation Branch is the administrative organization within the United States Army responsible for doctrine, manning and configuration for all army aviation units. After the United States Army Air Corps grew into the Army Air Forces and split into the new service, the United States Air Force, the Army was left with its sole fixed-wing aviation units flying Taylorcraft L-2 Grasshopper observation planes for artillery units. The Army would develop a new concept of aviation using the helicopter that would show promise during the Korean War and would revolutionize warfare during the Vietnam War.