Very few combat aircraft fought in World War II, Korea En Vietnam. The Invader did all three — not as a museum curiosity dragged out of storage, but as a front-line weapon each time. In 1944–45 it was a fast Ninth Air Force attack bomber over Europe. Renamed B-26 in 1948, it flew the Korean War’s lonely night-interdiction campaign, and USAF crews flew the war’s last bombing sortie in an Invader minutes before the 1953 armistice. A decade later, rebuilt as the B-26K, it was killing trucks on the Ho Chi Minh Trail. That longevity came from a simple truth: for hunting soft targets at low level, day or night, a rugged, heavily armed piston twin with long endurance was hard to beat — and nothing in the jet age quite replaced it until the dedicated gunships and the A-1 Skyraider took over the role.

There were two completely different American “B-26s.” The first was the Martin B-26 Marauder, a WWII medium bomber. The second was the Douglas Invader — built as the A-26 under the old “A” (attack) category. When the USAF dropped the separate attack category and the Martin Marauder was withdrawn, the Invader was redesignated B-26 in 1948, inheriting the very number its predecessor had just vacated. So a “B-26” in 1944 is a Martin Marauder; a “B-26” in 1951 is a Douglas Invader. Douglas re-adopted the “A-26” label again in Vietnam for political reasons — the B-26K was briefly re-styled A-26A so it could be based in Thailand, where “bombers” were not welcome. Few aircraft have generated as much honest confusion.

The first Invaders sent to Vietnam were worn-out war-surplus machines, and in 1964 a series of in-flight wing failures forced their withdrawal. Rather than abandon a proven weapon, the USAF had On Mark Engineering remanufacture the type. The resulting B-26K (first YB-26K in 1963) had strengthened wings with a redesigned spar, more powerful water-injected R-2800 engines, reversible propellers for short fields, permanent wingtip fuel tanks, and eight underwing pylons. Ordnance capacity rose from around 6,000 to roughly 12,000 lb. Redesignated A-26A to sidestep basing politics in Thailand, these aircraft flew night interdiction over Laos until November 1969.

As a mass-produced 1940s military aircraft, the Invader never had an open-market price, and figures vary by source and year. A wartime flyaway cost is commonly cited in the region of $192,000 to $250,000 — roughly comparable to other twin-engine attack bombers of the period — but that should be read as an order-of-magnitude estimate rather than a precise ledger figure. No credible modern cost-per-flight-hour number exists for the type; today the meaningful costs are those of keeping a handful of warbird Invaders airworthy, which run into the many hundreds of dollars per hour in fuel alone for two thirsty R-2800 radials. Any exact dollar figure attached to an A-26 is, in practice, an estimate.