I’ve written several times about seacoast fortifications, primarily because of my interest in Fort Casey where I grew up. Most of the fortifications I’ve written about have been what are known as Endicott-period fortifications.
After the Spanish-American War of 1898, the US suddenly found itself in possession of significant overseas territories for the first time. As a result of the war, the Taft Board made technical suggestions for the improvement of Endicott period fortifications, and also made recommendations for the defense of those overseas territories, primarily the Philippines. And the focus of the seacoast defense of Philippines was Manila Bay. Several Endicott style forts were built to guard Manila Bay from any seaward assault. The most famous fortifications guarding Manila Bay are probably those on Corregidor, where GEN MacArthur retreated to from the Bataan Peninsula (which forms the northern boundary of the bay).
Just south of Corregidor, near the southern edge of the bay, was a small uninhabited islet, El Fraile Island.
At just over 11 miles across, the mouth of Manila Bay was just wide enough that forts on both sides would be needed.
The Army thought El Fraile Island would be a nifty spot for a fort, situated as it was right at the chokepoint of the inlet. But as you can see from the picture above, it wasn’t exactly prime real estate.
So the Army made a pretty radical decision. They razed the island to just above the high water mark, and turned it into a concrete battleship. Really.
A massive casemate was built, with walls 25-40 feet thick, and a roof up to 18 feet thick of reinforced concrete. Two turrets with two 14” rifles each were installed, with a lattice fire control tower similar to those aboard contemporary US Navy battleships. Interestingly, the turrets were not identical to those used on 14” gun armed battleships, but were designed specifically for this fort. Four casemated 6” guns, and a pair of 3” anti-aircraft guns rounded out the armament. It was roughly 350 feet long, 144 feet wide, and the main deck rose 40 feet above high water.
Soon named Fort Drum, the battery had much of the features of a seagoing battleship. While it obviously didn’t have any propulsion, it did have an engine room, providing power to the guns and the garrison. There were crews quarters, officer staterooms, a fire control plot, facilities for small boats and resupply ships.
When the Japanese Army invaded the Philippines in World War II, the avoided directly assaulting Manila Bay. Instead, they landed well north, and fought their way toward the capital. One might argue that the presence of formidable defenses such as Fort Drum influenced that decision.*
As the Japanese pushed US and Filipino forces onto the Bataan Peninsula, and eventually onto Corregidor, Fort Drum came under fire from heavy siege guns. For all the shelling, only the most superficial damage was suffered. The surrender of Corregidor, and the lack of any resupply of fresh water, however, doomed Fort Drum. In May of 1942, the fort surrendered to Japanese forces. It should be noted that not a single member of the garrison had been killed, and only five wounded. Far more ghastly casualties would befall the 400 man garrison as POWs. And before they shuffled off into captivity, they sabotaged the guns of the fort so the Japanese would not be able to use them. Instead, the Japanese would maintain only a small garrison on the fort, mostly as an early warning post.
When US forces attacked in 1945 to wrest control of Manila from Japan, reduction of Fort Drum was postponed until all other resistance in the region had been destroyed. Then, a small raiding party was landed in a carefully planned assault, flooded the fort with a mixture of oil and gasoline via vents, and lit the mixture. The resulting fire incinerated the Japanese defenders, and gutted the fort from internal explosions. Since then, the ghostly hulk of the concrete battleship has stood abandoned, a guard at the mouth of Manila Bay.
Starboard beam view of the battleship USS NEW JERSEY (BB-62) passing between CORREGIDOR (background) and FORT DRUM as she enters Manila Bay.
*It should be noted that at the time Fort Drum and other Endicott forts were erected, an over the shore amphibious invasion was seen as almost impossible, not so much for landing the troops, but for landing the follow on supplies they would need. By 1942, the state of the art had progressed enough that such landings, while challenging, were feasible.