Liveblogging World War II: December 10, 1942

No Turning Back: Final Decisions and Presidential Approval | The Manhattan Project: Making the Atomic Bomb | History of the Atomic Age | atomicarchive.com:

The S-1 Executive Committee met to consider the Lewis report on December 9, 1942, just weeks after Allied troops landed in North Africa. Most of the morning session was spent evaluating the controversial recommendation that only a small electromagnetic plant be built. Lewis and his colleagues based their recommendation on the belief that Lawrence could not produce enough uranium-235 to be of military significance. But since the calutron could provide enriched samples quickly, the committee supported the construction of a small electromagnetic plant. Conant disagreed with the Lewis committee's assessment, believing that uranium had more weapon potential than plutonium. And since he knew that gaseous diffusion could not provide any enriched uranium until the gaseous diffusion plant was in full operation, he supported the one method that might, if all went well, produce enough uranium to build a bomb in 1944. During the afternoon, the S-1 Executive Committee went over a draft Groves had prepared for Bush to send to the President. It supported the Lewis committee's report except that it recommended skipping the pilot plant stage for the pile. After Conant and the Lewis committee met on December 10 and reached a compromise on the electromagnetic method, Groves' draft was amended and forwarded to Bush…