This is apocryphal, but it probably had something to do with dropping shells on Nazis - he was developing fire control systems for the US Navy around the time h

This is apocryphal, but it probably had something to do with dropping shells on Nazis - he was developing fire control systems for the US Navy around the time he developed the theorem, and only published several years after the War. Allegedly he also derived Mason's Gain Formula around the same time but that was classified until Mason published it.