Fort Drum, originally known as El Fraile Island, is a huge, now ruinous complex of concrete and steel that once guarded the southern entrance to Manila bay. It’s consutuction and took years and for much of it’s history, it was regarded as strange, unique oddity on the horizon of manila bay.
For a brief few months amid the desperate defence of the Philippines during WWII, it proved to be a formible and impervious foe. Nicknamed a “concrete battleship”, the reinforced concrete sea fort, shaped like a battleship, was built by the United States in 1909 as one of the harbor defenses at the wider South Channel entrance to the Bay during the American colonial period.Video by:Calum
Initially, Fort Drum was planned as a mine control and casemate station. However, due to inadequate defences in the area, a plan was devised to level the island, and then build a concrete structure on top of it armed with four 12-inch (305 mm) guns in twin mounts.This was submitted to the War Department, which decided to change the 12-inch (305 mm) guns to 14-inch (356 mm) guns mounted in twin armoured turrets.
The forward turret, with a traverse of 230°, was mounted on the forward portion of the upper deck, which was 9 ft (2.7 m) below the top deck; the rear turret, with a full 360° traverse, was mounted on the top deck. The guns of both turrets were capable of 15° elevation, giving them a range of 19,200 yards (17,600 m).Secondary armament was provided by two pairs of 6-inch (152 mm) guns mounted in armoured casemates on either side of the main structure./wikipedia