By the summer of 1941, the War Department work force in the Washington, D.C. area numbered more than 24,000 civilian and military personnel housed in 17 buildings and was expected to reach 30,000 by the beginning of 1942. Providing office space for the workers was part of the military construction mission of the Quartermaster Corps Construction Division who were struggling to cope with the vast mobilization construction underway before the United States entered World War II.
The federal government considered constructing temporary buildings, but Brigadier General Brehon B. Somervelle, an aggressive Engineer officer who headed the construction division, had another idea. On Thursday, 17 July 1941, he summoned two of his subordinates, Lieutenant Colonel Hugh J. Casey, also an Engineer officer, and George E. Bergstrom, a prominent civilian architect. He told them that by Monday morning he wanted basic plans and an architectural perspective for an air-conditioned office building to house 40,000 workers in four million square feet of space, not more than four stories high, with no elevators. Indeed, Lieutenant Colonel Casey and his staff completed the basic layout of a five-sided building by that following Monday, after what he later described was "a very busy weekend."
The War Department staff approved the building's basic concept that Monday and the Secretary of War approved it on Tuesday, informing President Franklin D. Roosevelt of his plans. Also on Tuesday Somervell took the plan to Congress. Sensitive to the severity of the space problem, Congress and the president moved quickly to approve a supplemental defense appropriation bill, including $35 million for the construction of the proposed War Department headquarters.
The plans underwent many changes in the next few months, including changes in location. With Somervell's approval, Casey and Bergstrom sited the building between Arlington National Cemetery and Memorial Bridge. Some federal agencies and local citizens did not want the proposed building to obstruct the vista between the Lincoln Memorial and Arlington Cemetery. Appeasing opponents, in August President Roosevelt moved the site to its current location.
Plans for the building proceeded swiftly. Bergstrom with architect David J. Witmer developed plans for a unique reinforced concrete building that would consist of five concentric pentagons separated by light wells and connected by radiating spoke-like corridors. It would have five stories and include a six-acre interior court, numerous ramps and escalators, a large shopping concourse on the first floor, taxi stands and bus lanes, and parking for 8,000 cars.