The B-26K is a bit of a confusing thing, in no small part thanks to re-used nomenclature. It started out as the A-26 Invader in 1943, while the B-26 Marauder was still in service. In 1948, the A-26 was then re-designated the B-26 after the Marauder was retired.
One of the most striking things about the A-26/B-26 crafts’ history is the number of times they were called back to service. First used in WWII (and appreciated for its large bomb load and abilities in a ground-attack role), it was retired, then brought back for service in Korea, then retired again, then brought out of retirement for use in Southeast Asia, then retired, then brought back for use in Vietnam and Thailand, then finally retired for good. Meanwhile, they made appearances in conflicts in Africa, and played a big role (on both sides) at the Bay of Pigs invasion of Cuba in 1961.
After their military days were over, a number of A-26s were converted for use as “slurry bombers,” helping put out forest fires.
From the placard:
The Counter Invader was a highly modified version of the Douglas A-26 Invader, a WWII attack bomber. Redesignated B-26 in 1948, the Invader served again during the Korean War, mainly as a night intruder against North Korean supply lines. It was removed from service in 1958, but in 1961 the USAF recalled many Invaders for use as tactical bombers in Southeast Asia. In 1964, the B-26 again were removed from service.
In 1966, the old bomber was resurrected once more when the improved B-26K Counter invader returned for ground-attack missions along the Ho Chi Minh Trail. The B-26K had a rebuilt fuselage and tail, strengthened wings, improved engines, and other refinements.
The B-26K remained in Southeast Asia until 1969, then were removed for disposal.