<P> Both the United States and Japan accelerated the training of aircrew, but the United States had a more effective pilot rotation system, which meant that more veterans survived and went on to training or command billets, where they were able to pass on lessons they had learned in training, instead of remaining in combat, where errors were more likely to be fatal . By the time of the Battle of the Philippine Sea in June 1944, the Japanese had nearly rebuilt their carrier forces in terms of numbers, but their planes, many of which were obsolescent, were largely flown by inexperienced and poorly trained pilots . </P> <P> Midway showed the worth of pre-war naval cryptanalysis and intelligence - gathering . These efforts continued and were expanded throughout the war in both the Pacific and Atlantic theaters . Successes were numerous and significant . For instance, cryptanalysis made possible the shooting down of Admiral Yamamoto's airplane in 1943 . </P> <P> The Battle of Midway redefined the central importance of air superiority for the remainder of the war when the Japanese suddenly lost their four main aircraft carriers and were forced to return home . Without any form of air superiority, the Japanese never again launched a major offensive in the Pacific . </P> <P> Because of the extreme depth of the ocean in the area of the battle (more than 17,000 ft or 5,200 m), researching the battlefield has presented extraordinary difficulties . On 19 May 1998, Robert Ballard and a team of scientists and Midway veterans from both sides located and photographed Yorktown . The ship was remarkably intact for a vessel that had sunk in 1942; much of the original equipment and even the original paint scheme were still visible . </P>

As a result of the battle of midway