By the middle of 1941, World War 2 as in full swing and American authorities looked into the possibility of the United States being pulled into the conflict - particularly if allied Britain were to fall as did France. This spurred the United States Army Air Corps (USAAC) to seek out a new all-modern, long-range heavy bomber with capabilities to fly outside of the reach of enemy air defenses (including interceptors) and far into enemy-held territory. Douglas aircraft was one of the firms to respond to the requirement and delivered their Model 423 as a result. The competition was eventually won by a design put forth by Consolidated which went on to become the post-war B-36 "Peacemaker".
The Douglas entry relied on 4 x Pratt & Whitney R-4360 "Wasp Major" air-cooled radial piston engines, each outputting 3,000 horsepower. As drawn up, the aircraft exhibited a length of 35.75 meters with a wingspan reaching 63.09 meters and a height of 14.5 meters. Maximum Take-Off Weight (MTOW) was in the vicinity of 90,000 kilograms. Douglas engineers suggested their aircraft could have a range out to 9,654 kilometers.
Internally there would be a crew of eight to man the various positions about the aircraft. One key physical characteristic of the design was its pilot's set within individual bubble-style canopy cockpits along the forward section of the airframe. The bomb bay would hold upwards of 11,340 kilograms of conventional drop munitions. Up to six 0.50 caliber Browning M2 heavy machine guns, set in three remote-controlled power-operated turrets (one dorsally, one ventrally, one at the tail) would be featured to defend the aircraft from enemy fighters.
In the end, the Model 423 fell by the wayside as the Consolidated B-36 program was selected and pushed to operational-level service. A first-flight of a prototype was had in August of 1946, at which time the war was all but over, and service entry occurred in 1949 - much too late to make any sort of impact in World War 2.