World War II

The U.S. Navy grew into a formidable force in the years prior to World War II, with battleship production being restarted in 1937, commencing with USS North Carolina (BB-55). Though ultimately unsuccessful, Japan tried to neutralize this strategic threat with the surprise attack on Pearl Harbor on 7 December 1941. Following American entry into the war, the U.S. Navy grew tremendously as the United States was faced with a two-front war on the seas. It achieved notable acclaim in the Pacific Theater, where it was instrumental to the Allies' successful "island hopping" campaign.^[23] The U.S. Navy participated in many significant battles, including the Battle of the Coral Sea, the Battle of Midway, the Solomon Islands Campaign, the Battle of the Philippine Sea, the Battle of Leyte Gulf, and the Battle of Okinawa. By 1943, the navy's size was larger than the combined fleets of all the other combatant nations in World War II.^[39] By war's end in 1945, the U.S. Navy had added hundreds of new ships, including 18 aircraft carriers and 8 battleships, and had over 70% of the world's total numbers and total tonnage of naval vessels of 1,000 tons or greater.^[40][41] At its peak, the U.S. Navy was operating 6,768 ships on V-J Day in August 1945.^[42]

Doctrine had significantly shifted by the end of the war. The U.S. Navy had followed in the footsteps of the navies of Great Britain and Germany which favored concentrated groups of battleships as their main offensive naval weapons.^[43] The development of the aircraft carrier and its devastating use by the Japanese against the U.S. at Pearl Harbor, however, shifted U.S. thinking. The Pearl Harbor attack destroyed or took out of action a significant number of U.S. Navy battleships. This placed much of the burden of retaliating against the Japanese on the small number of aircraft carriers.^[44] During World War II some 4,000,000 Americans served in the United States Navy.^[45]