If you want a long book that has a much wider compass than Lemay alone, read Rhodes' "The Making of the Atomic Bomb." Lemay plays a major role, of course, at the end. It's a fascintating story about people, physics, spies, politics, war strategy, tactics, engineering, Japanese and German nuclear programs, antisemitism in Germany, etc. I could go on, but you get the idea of the scope of the book. Highly recommended if you want to see where Lemay fit in the big picture.
Thanks! Added to the list!