I have a question for the HN community. What exactly was Szilard's contribution to the Manhattan project, aside from the initial letter that started it all? I k

I have a question for the HN community. What exactly was Szilard's contribution to the Manhattan project, aside from the initial letter that started it all? I know that Szilard was the first to envision the idea of chain reaction, and got a (secret) patent for that, but at the time it was more or less idle speculation. When the project actually got going, I know he collaborated with Fermi on the Chicago pile reactor, but 99% of the accomplishment was due to Fermi, not to Szilard. After that, Szilard remain a towering figure inside the project, but did he actually contribute anything?