Corregidor (Tagalog: Pulo ng Corregidor, [kɔˈɾɛhidɔr]) is an island located at the entrance of Manila Bay in the southwestern part of Luzon in the Philippines, and is considered part of the Province of Cavite. Due to this location, Corregidor has historically been fortified with coastal artillery batteries to defend the entrance of Manila Bay and Manila itself from attacks by enemy warships. Located 48 kilometres (30 mi) inland, Manila is the nation's largest city and has been the most important seaport in the Philippines for centuries, from the colonial rule of Spain, Japan, and the United States, up through the establishment of the Third Philippine Republic in 1946.