check, estimated that the critical mass of a sphere of Uranium-235 was in the range of 2.5 to 5 kilograms, with a destructive power of around 2,000 tons of TNT. Moreover, it appeared that plutonium might be even more fissile. After conferring with Brigadier General Lucius D. Clay about the construction requirements, Bush drew up a submission for $85 million in fiscal year 1943 for four pilot plants, which he forwarded to Roosevelt on June 17, 1942. With the Army on board, Bush moved to streamline oversight of the project by the OSRD, replacing the Section S-1 with a new S-1 Executive Committee. Bush soon became dissatisfied with the dilatory way the project was run, with its indecisiveness over the selection of sites for the pilot plants. He was particularly disturbed at the allocation of an AA-3 priority, which would delay completion of the pilot plants by three months. Bush complained about these problems to Bundy and Under Secretary of War Robert P. Patterson. Major General Brehon B. Somervell, the commander of the army's Services of Supply, appointed Brigadier General Leslie R. Groves as project director in September. Within days of taking over, Groves approved the proposed site at Oak Ridge, Tennessee, and obtained a AAA priority. At a meeting in Stimson's office on September 23 attended by Bundy, Bush, Conant, Groves, Marshall Somervell and Stimson, Bush put forward his proposal for steering the project by a small committee answerable to the Top Policy Group. The meeting agreed with Bush, and created a Military Policy Committee chaired by him, with Somervell's chief of staff, Brigadier General Wilhelm D. Styer, representing the army, and Rear Admiral William R. Purnell representing the navy. At the meeting with Roosevelt on October 9, 1941, Bush advocated cooperating with the United Kingdom, and he began corresponding with his British counterpart, Sir John Anderson. But by October 1942, Conant and Bush agreed that a joint project would pose security risks and be more complicated to manage. Roosevelt approved a Military Policy Committee recommendation stating that information given to the British should be limited to technologies that they were actively working on and should not extend to post-war developments. In July 1943, on a visit to London to learn about British progress on antisubmarine technology, Bush, Stimson, and Bundy met with Anderson, Lord Cherwell, and Winston Churchill at 10 Downing Street. At the meeting, Churchill forcefully pressed