[2] A redesignation of the type from A-26 to B-26 has led to confusion with the earlier and unrelated Martin B-26 Marauder,[3] which had already been withdrawn from service when the designation was reused.

Designed by Ed Heinemann, Robert Donovan, and Ted R. Smith,[4] the innovative NACA 65-215 laminar-flow airfoil wing of the A-26 was the work of project aerodynamics expert A.M.O.

Flight tests revealed excellent performance and handling but engine-cooling problems led to cowling changes and elimination of the propeller spinners on production aircraft.

In most missions, a third crew member in the rear gunner's compartment operated the remote-controlled dorsal and ventral gun turrets, with access to-and-from the cockpit via the bomb bay only if that was empty.

As he pressed the handles downward, and as the bead passed the centerline, the mirror automatically flipped, transferring the sight "seamlessly" to the lower periscope.

While novel and sound in principle, the developers invested a great deal of time and effort in their attempts to get the system to work, delaying production.

[11] Douglas officially delivered the first production model A-26B aircraft to the United States Army Air Forces (USAAF) on 10 September 1943.

The A-26 first saw action on 23 June 1944, when four aircraft attached to the 3rd Bombardment Group's 13th Squadron ("The Grim Reapers"), bombed Japanese-held islands near Manokwari.

[13] Aircrew from "The Grim Reapers", while evaluating these four A-26Bs, noted that downward views from the cockpit were significantly hindered by the nature of the design – especially the positioning of the engines – which made the A-26B unsuitable for its intended role of ground attack.

[15] Douglas needed better results from the Invader's second combat test, so ferried A-26s arrived in Europe in late September 1944 for assignment to the Ninth Air Force.

No aircraft were lost on the eight test missions, and the Ninth Air Force announced they were satisfied, eventually replacing their A-20s and B-26s with the A-26 Invader.

In contrast to the Pacific-based units, the A-26 was well received by pilots and crew alike, and by 1945, the 9th AF had 11,567 missions, dropping 18,054 tons of bombs, recording seven confirmed kills while losing 67 aircraft.

They were used against German transport links, and for direct support and interdiction against tanks and troop concentrations in the Po Valley in the final campaigns in Italy.

In June 1951, they joined the 3rd Bomb Wing (Kunsan (K-8)) in night activity only, dividing the target areas, with the 452nd taking the eastern half and the 3rd the western.

[25] The aircraft from Laos participated in the early phase of the Vietnam War with the USAF, but with Vietnamese markings as part of Project Farm Gate.

The two aircraft returned from Black Watch to Farm Gate were redesignated RB-26L to distinguish them from other modified RB-26Cs, and were assigned to Project Sweet Sue.

[30] In response to this, the On Mark Engineering Company of Van Nuys, California, was selected by the USAF to extensively upgrade the Invader for its new counterinsurgency role.

On Mark converted 40 Invaders to the new B-26K Counter-Invader standard of upgraded engines, propellers, and brakes, remanufactured wings, and wing-tip fuel tanks for use by the 609th Special Operations Squadron.

Two of these aircraft were modified with a forward-looking infrared (FLIR) system under project Lonesome Tiger, as a part of Operation Shed Light.

After transfer to Nicaragua in early April 1961, they were painted in the markings of the Fuerza Aérea Revolucionaria (FAR), the air force of the Cuban government.

[32][33][34] The CIA contracted pilots, some employed during the Bay of Pigs Invasion, to fly B-26Ks for ground attack against Simba rebels in the Congo Crisis.

In this period, a massive use of Philippines-based USAF B-29s against the Viet Minh heavy artillery, including the potential use of nuclear weapons, was planned by the U.S. Joint Chiefs of Staff with the French as Operation Vulture, but was cancelled by the governments,[36] while at the conclusion of the battle, some of the beleaguered French troops managed to escape through the jungle to neighboring Thailand.

Concerned about Indonesian President Sukarno's communist leanings, the CIA started Operation Haik in 1958 to overthrow his Guided Democracy in Indonesia regime.

[38] The capture and trial of Lieutenant Pope brought a quick end to Operation Haik, but the capabilities of the Invader were not lost on the Indonesian government.

[48] The initial main civil uses were as "executive" personnel transports with minimal modifications such as removal of military features, bomb-bay doors sealed shut, passenger-entry stairs in bomb bay, and the conversion of the fuselage to accept six to eight passengers.

[49] During the mid-1950s, A-26s were tested and used as air tankers for suppression of forest and wildland fires, and briefly used borate-based retardants, hence the inaccurate and unofficial term "borate bombers".

Borate was later discontinued due to its undesirable ecologic effects, replaced with retardant mixtures of water, clays, fertilizers, and red dyes.

[10] Much early development of conversions was carried out by Grand Central Aircraft, whose drawings and personnel were taken up by the On Mark Engineering Company of Van Nuys, California, from about 1955.

[54][55]General characteristics Performance Armament In July 2005, the archaeological television program Time Team of the UK's Channel 4, along with members of RAF Millom Museum, took part in a major project to excavate the crash sites of two A-26 Invader aircraft after the aircraft collided shortly after take-off over marshes close to the then USAAF BAD 2 airbase at Warton in Lancashire on 29 November 1944.