In the Battle of the Atlantic, aircraft carried by low-cost escort carriers were used for antisubmarine patrol, defense, and attack. At the start of the Pacific War in 1941, Japanese carrier-based aircraft sank several US battleships at Pearl Harbor and land-based aircraft sank two large British warships. Engagements between Japanese and American naval fleets were then conducted largely or entirely by aircraft including the battles of Coral Sea, Midway, Bismarck Sea and Philippine Sea.