As expert as both Germany and Japan were in the application of air power against weaker opponents, neither nation had any concept of the scale of air power that was required to fight a global war. Both believed that air forces of 3,000 to 5,000 front-line planes, flown by expert crews, were adequate. Both were wrong by a factor of 15 or more.
Of all the nations involved in the war, only the United States and the Soviet Union understood just how large an effective air force would have to be. They also had the industrial capacity to create such a force. Great Britain understood that a large air force was needed but despite its best efforts could not create one of the necessary size, because it devoted far too many resources to its Bomber Command.
Germany began the war against the Soviet Union with fewer first-line aircraft available than it had at the time of the fall of France. In the first few months of the war, the Luftwaffe was able to decimate the Soviet Air Force--but it could not reach either the Soviet aircraft factories or training bases. Japan began the war with clearly superior aircraft and crews but had such a small industrial base and an even smaller crew training system that it could not replace the losses incurred in the Battles of the Coral Sea and Midway.
By 1943, the tide was shifting swiftly away from the once victorious Axis powers to the Allies and to the Soviet Union. In the United States, new aircraft were coming off the factory lines in ever increasing numbers, and pilots and crews were flowing at an inexhaustible rate. The Soviet Union was also beginning to feel its new strength, with more and better aircraft racing off production lines. While Germany and Japan made enormous efforts to catch up, both timing and technology were now firmly on the side of the Allies.
Airpower through 1943 had been important in many instances, decisive in a few but always influential. However, the groundwork in airpower, training, and armament had been laid so that the Allies could forge ahead in the next two years of the war and utterly defeat the countries that had started the war. In the process, they would build the technical foundation for a revolution in civil and military aviation in the postwar period. For the next chapter in flight history, check out Post-World War II Flight.