The Martin B-26 Marauder, a twin-engine light bomber, entered U.S. Army Air Forces service in 1941. Over 5,000 were built, and the aircraft were used in all theaters of operations. All Martin B-26s were declared obsolete by the United States Air Force in 1948, but few had survived even until that date as airworthy aircraft. The B-26 designation was transferred to the Douglas A-26 in June 1948 after the Martin bomber was withdrawn from service.
The Douglas A-26 Invader, a twin-engine
attack aircraft, was used operationally for the first time in 1944. The A-26 was
operational in the Pacific in the later stages of the campaign against Japan. It remained
in frontline service after the end of World War II, particularly as the principal
offensive weapon of Tactical Air Command (TAC), when it was created in 1946 from the
wartime Ninth and Twelfth Air Forces.
In June 1948, the attack category for aircraft mission designation was officially abandoned by the U.S. Air Force. The designation of the Douglas A-26 was changed to B-26. Concurrent with this change, the Martin B-26 Marauder was withdrawn from service. The Douglas B-26s were used extensively for night interdiction missions flown by the 3rd Bombardment Group from Iwakuni, Japan, during the Korean War.
The B-26 remained in service with the Air Force Reserve and National Guard units after being retired by TAC. It was available to return to operational service in Vietnam in 1962, and both the B-26B and B-26C versions saw action in counterinsurgency missions.
In 1963, the U.S. Air Force initiated development of a prototype designated YB-26K in an attempt to increase the load-carrying ability and short-field performance of the B-26 airframe. In 1967, the Air Force ordered about seventy B-26s to be converted to B-26K specifications after evaluating the YB-26K's performance. Some of the Douglas B-26Ks saw service in Vietnam after being redesignated A-26As .