The Douglas DB-73 was basically the French equivalent of the DB-7B that was ordered by the Royal Air Force. It was basically similar to the DB-7B for the RAF, but differed primarily in being fitted with French equipment and instruments. 480 DB-73s were ordered by France on May 18, 1940, but none had been delivered by the time that France fell. Consequently, all the DB-73s ordered were completed to DB-7B standards following the French capitulation and were delivered to Britain as Boston IIIs.
Power was provided by two 1600 hp Wright R-2600-A5B radials. Total fuel capacity was increased from 205 US gallons to 394 gallons in order to improve the range so that the aircraft could operate against targets in occupied Europe.
The first batch of 240 (AL263/AL502) were built by Douglas-Santa Monica, but the second batch of 240 (AL668/AL907) were built by Boeing-Seattle, which had acquired a license from Douglas at the time of the French order. Boeing had actively sought out this additional business, since they had experienced difficulty in selling B-17s to the US Army. The details were worked out before the French contract was signed, and it was agreed that Douglas would provide drawings, tooling and some production personnel to Boeing. The Boeing-built machines differed from the Douglas-built Boston IIIs only in their electrical systems, in the removal of the "alligator-tail" flame-damping exhaust pipes in favor of ventral stubs, and in the extensions of the carburetor air intakes forward over the type of the cowling to include tropical air filters.
In addition one DB-7B (AH740) was delivered as a replacement for the DB-7A (AH430) which had crashed in the USA before delivery.
Most of the RAF DB-7B aircraft never did reach Britain. Large numbers were diverted to the Soviet Union following the German attack on June 22, 1941, with some 151 of the order ending up going to the Russians. Following the American entry into the war, substantial numbers of Bostons destined for the RAF were requisitioned by the USAAF. Some 162 Douglas-built and 194 Boeing-built Bostons ended up being seized by the USAAF in this manner.
It was not until late 1942 that the deliveries of Bostons to Britain were resumed. By this time, the deliveries to Britain were being carried out under the terms of Lend-Lease rather than as direct purchases. The aircraft designated for delivery to Britain were given USAAF designations of A-20C and were assigned USAAF serial numbers. They were known as Boston IIIA in RAF service. They were basically similar to the USAAF A-20C, with the exception of the use of British equipment and armament. RAF serials were BZ196/BZ352, BZ355/BZ378, and BZ381/BZ399. Other Boston IIIAs were taken over in the field by the RAF, some of them retaining their original USAAF serial numbers, while others received new RAF serials (HK869, HK870, HK872/HK879, HK912, HK918, HK923, HK924, HK934, HK960, HK962, HK964, HK967, HK969, HK970, HK972, and HK973).
The following 22 Boston III and IIIAs were diverted to the Royal Australian Air Force (RAAF):
AL890 to RAAF as A28-1 3/42 AL347 to RAAF as A28-2 3/42 AL887 to RAAF as A28-3 3/42 AL893 to RAAF as A28-4 3/42 AL895 to RAAF as A28-5 3/42 AL897 to RAAF as A28-6 3/42 AL899 to RAAF as A28-7 3/42 AL907 to RAAF as A28-8 3/42 AL891 to RAAF as A28-9 3/42 AL358 to RAAF as A28-10 3/42 AL364 to RAAF as A28-11 3/42 AL365 to RAAF as A28-12 3/42 AL367 to RAAF as A28-13 3/42 AL892 to RAAF as A28-14 3/42 AL361 to RAAF as A28-15 3/42 AL362 to RAAF as A28-16 3/42 AL363 to RAAF as A28-17 3/42 AL366 to RAAF as A28-18 3/42 AL368 to RAAF as A28-19 3/42 AL369 to RAAF as A28-20 3/42 AL894 to RAAF as A28-21 3/42 AL898 to RAAF as A28-22 3/42
AL263/AL502 Douglas Boston III AL444 wrecked at Portland, Arkansas Feb 12, 1942 AL447 wrecked at Will Rogers Field, OK Jun 26, 1943. AL448 wrecked at Fairfax Airport, Kansas Dec 23, 3943 AL450 crashed Mar 20, 1943, Shipham, UK due to structure failure. Crew bailed out AL453 crashed Oct 24, 1942 at Blythe AAB, CA AL485 condemned after crtashe in USA Feb 1, 1942 AL487 wrecked in river off Bolling Field, Washington, DC Feb 20, 1942. AL668/AL907 Douglas Boston III AL838 ditched in Neuse River, North Carolina Jul 4, 1942. Plane never recovered AL867 crashed off Reedville, VA in Chesapeake Bay Apr 16,1942. One missing.