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