The Japanese Air Force, in 1941, was the best trained and most powerful carrier air forces in the world.And until 1943, they destroyed their opponents so swiftly that the Japanese nation considered it invincible.But, this was bad for them also.Just as with the Luftwaffe, the Japanese did not replace their front-line types until it was too late.The Zero, for instance, should have been replaced by the A7M Reppu in 1943, but it wasn't and by the time the prototype was ready to go, the war was over.But, before their downfall, the Japanese Air Force was unstoppable.They caused so much destruction and utter dismay to the Allies that their wasn't much for them to do but run.