In 1941, commanding the Pacific Fleet aircraft carriers, he and his fleet were out of harbour when the Japanese attacked Pearl Harbor. In 1942 he led a spectacular raid against the Marshall and Gilbert Islands and during the campaign of the Solomon Islands he took command of the South Pacific area. As commander of the 3rd Fleet at the Battle of Leyte Gulf (1944), he sank a number of Japanese aircraft carriers and in 1945 led the seaborne bombing offensive against Japan.