The correct answer is The Battle of Midway.
The Battle of Midway is considered a turning point for the US military during World War II. Just 6 short months after the US entered the war, they were fighting against Japan at Midway. This battle had strategic implications, as a Japanese win would result in Japan controlling almost all the important locations in the Pacific Ocean. Even though the US had less planes, aircraft carriers, etc., they still managed to beat the Japanese. One of the biggest factors behind this was the decoding of the Japanese strategy for this battle.