Corregidor in Cavite Province is the largest of the islands that formed the harbor defenses of Manila Bay together with El Fraile Island, Caballo Island and Carabao Island, which were all fortified during the American liberation of the country. During World War II, Corregidor played an important role during the invasion and liberation of the Philippines from Japanese forces. Heavily bombarded in the latter part of the war, the ruins left on the island serve as a military memorial to American, Filipino and Japanese soldiers who served or lost their lives on the island. Corregidor is one of the important historic and tourist sites in the country.