Which 1942 battle established American naval supremacy in the Pacific primarily through carrier power and code-breaking?

• A. Battle of Guadalcanal
• B. Battle of Coral Sea
• C. Battle of Leyte Gulf
• D. Battle of Midway

Answer: (D)

The key idea this item tests is how a decisive use of aircraft carriers combined with crucial intelligence can tilt a war at sea. At Midway in 1942, American forces turned the tide by leveraging a breakthrough in code-breaking to learn the Japanese plan and timing, which allowed them to set a trap for the enemy fleet. The United States then struck with its carrier air power, while the Japanese adversary lost four frontline carriers in a single battle. That staggering loss crippled Japan’s ability to wage offensive carrier warfare and left the United States with the initiative to project power across the Pacific.

This is what makes Midway stand out: it shows that air power from carriers could decisively defeat a fleet when backed by cryptanalytic intelligence that reveals the enemy’s plans. The other battles, while important in their own right, do not embody this combination as clearly or as early in the war. Guadalcanal features a grueling campaign across land and sea without the same decisive demonstration of carrier supremacy secured by code-breaking. Coral Sea marked a halt to a Japanese advance and showcased carrier actions, but it was more of a tactical and operational stalemate than a defining shift in balance. Leyte Gulf, while a huge carrier battle, occurred later in 1944 and isn’t the 1942 moment that established American naval dominance.