I had always heard that we only had the two atomic bombs. Now they’re saying we had more?
They were under construction.
Document 67: General L. R. Groves to Chief of Staff George C. Marshall, August 10, 1945, Top Secret
Source: George C. Marshall Papers, George C. Marshall Library, Lexington, VA (copy courtesy of Barton J. Bernstein)
While Groves was making plans for the use of a third atomic weapon sometime after 17 August, depending on the weather, Marshalls note on this memo shows that he was following Trumans instructions to halt nuclear strikes: It is not to be released over Japan without express authority from the President.
Wasn’t there a third that was tested in the US prior to the missions in Japan?
Initially there was Trinity, the province. There was just enough fissionable material, both U238 and Plutonium for just one bomb each. There where plans for more but they weren’t made yet the time of the bombing.