What was the most significant early U.S. victory in the Pacific theatre?

The battle of Midway was the first major victory for American forces against the Imperial Japanese forces in the Pacific theatre of war. The battle of Midway took place in June1942 in which the American naval and air forces inflicted a major blow to imperial navy and air forces of Japan and destroyed all 4 Japanese aircraft carriers and were able to break the naval code of imperial navy(Japanese) which proved to be decisive in the future course of the war.