It operated in the Mediterranean Sea during World War II with a main mission of amphibious warfare, and then was active in 1946–47 as the heavy striking arm of the United States Atlantic Fleet.
Still under Hewitt's command, the renamed Eighth Fleet supported the landings in Sicily, Operation Husky, and at Salerno, Operation Avalanche, the first sustained land assault and invasion of the European mainland in World War II.
Hewitt remained as the fleet commander until 1945, when he moved on to chair a Pearl Harbor investigation.
With the reorganization of the Navy after World War II in December 1945, Eighth Fleet was reactivated on 1 March 1946 under the command of Admiral Marc A. Mitscher.
made up of USS Wisconsin and Missouri, retained under direct command of Atlantic Fleet.