In 1941 Douglas Aircraft Company began work on their twin-engine medium-bomber A-26 Invader. By the end of production there were 2,452 aircraft produced for all variants. The A-26/B-26 was the only U.S. bomber to take part in three wars, WWII, Korea and Vietnam. The confusion with the use of the designation B-26 began when the Martin B-26 Marauder was retired and in 1948 the USAF dropped the “A” (Attack) designator so the Douglas A-26 Invader became the B-26 Invader. The A-26 made its first European appearance in late 1944.

On Mark Engineers was given the job to convert B-26s to the K variant. B-26K Counter Invader AF64-646 joined the USAF on August 12, 1964 and assigned to the 1st Air Commando Wing and sent to the CIA in the Congo. In July 1967 the aircraft was assigned to the 634th Combat Support Group in Thailand and then in August the 56th Air Commando Wing, later becoming the 56th Special Operations Wing. On July 8, 1969 AF64-646 became the last B-26 lost during the Vietnam War when it hit a hillside during a strafing run.