Corregidor Island, locally called Isla ng Corregidor, is a lofty island located at the entrance of Manila Bay
Manila Bay
Manila Bay is a natural harbor which serves the Port of Manila , in the Philippines.The bay is considered to be one of the best natural harbors in Southeast Asia and one of the finest in the world...

 in southwestern part of Luzon Island in the Philippines. Due to this location, Corregidor was fortified
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

 with several coastal artillery
Coastal artillery
Coastal artillery is the branch of armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications....

 and ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...

Magazine (artillery)
Magazine is the name for an item or place within which ammunition is stored. It is taken from the Arabic word "makahazin" meaning "warehouse".-Ammunition storage areas:...

s to defend the entrance of Manila Bay and the City of Manila, from attacks by enemy warship
A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

s in the event of war. Located 48 kilometres (29.8 mi) inland, Manila has been the largest city and the most important seaport in the Philippines for centuries—from the colonial rule of Spain
Spanish Empire
The Spanish Empire comprised territories and colonies administered directly by Spain in Europe, in America, Africa, Asia and Oceania. It originated during the Age of Exploration and was therefore one of the first global empires. At the time of Habsburgs, Spain reached the peak of its world power....

, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and Japan and after the establishment of the Republic of the Philippines in 1946.

Corregidor (Fort Mills
Fort Mills
Fort Mills was the location of US Major General George F. Moore's headquarters for the Philippine Department's Harbor Defenses of Manila and Subic Bays. This was one of the locations at which, under the National Defense Act of 1935, coastal artillery training was conducted.-References:*McGovern,...

) is the largest of the islands that form the harbor defense of Manila Bay together with El Fraile Island (Fort Drum), Caballo Island
Caballo Island
Caballo Island is a bluff, rocky island located at the entrance to Manila Bay in the Philippines. It is about 3/4 mile long with the highest elevation at 381 feet high...

 (Fort Hughes
Fort Hughes
Fort Hughes was part of the harbor defenses of Manila and Subic Bays built by the Philippine Department of the U.S. Army in the early 1900s....

) and Carabao Island (Fort Frank
Fort Frank
Fort Frank was one of the defense forts at the entrance to Manila Bay established by the United States. The entire island was designated as Fort Frank, in honor of Brigadier General Royal T...

), which were all fortified during the American occupation
History of the Philippines (1898-1946)
This article covers the history of the Philippines from 1898 to 1946. It spans the Spanish-American War which resulted in the United States acquiring sovereignty over the Philippines from Spain via the Treaty of Paris which ended that war, the Philippines as a U.S. territory and later as a U.S...

 of the country.