How much did rivalry between the Imperial Japanese Army and Navy contribute to Japan's defeat?
Short answerIt made Japanese operations markedly worse, but even effective cooperation could only improve the terms and timing of defeat rather than secure victory.
NotesThe panel treats Japanese defeat as structurally unavoidable once the war took its historical form. Strategic cooperation might have produced less damaging defeats and much better intelligence sharing, especially by avoiding the absurd practice of routing locally obtained decrypts through Tokyo before passing them to a neighboring service unit. Better liaison could improve operational timing and reduce self-inflicted friction. It would not, however, create a path to outright victory over the United States or erase the Allied material advantage.