The Battle of the Philippine Sea was a major naval battle of World War II on 19–20 June 1944 that eliminated the Imperial Japanese Navy's ability to conduct large-scale carrier actions. It took place during the United States' amphibious invasion of the Mariana Islands during the Pacific War. The battle was the last of five major "carrier-versus-carrier" engagements between American and Japanese naval forces, and pitted elements of the United States Navy's Fifth Fleet against ships and aircraft of the Imperial Japanese Navy's Mobile Fleet and nearby island garrisons. This was the largest carrier-to-carrier battle in history, involving 24 aircraft carriers, deploying roughly 1,350 carrier-based aircraft.

The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the world's most powerful navy and the largest by tonnage, at 4.5 million tons in 2021 and in 2009 an estimated battle fleet tonnage that exceeded the next 13 navies combined. It has the world's largest aircraft carrier fleet, with 11 in service, 1 undergoing trials, two new carriers under construction, and six other carriers planned as of 2024. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the U.S. Navy is the third largest of the United States military service branches in terms of personnel. It has 299 deployable combat vessels and about 4,012 operational aircraft as of July 18, 2023.