More history for the day

War History Online has an article by Pio Andrade Jr. about the Philippines:

As one enters and exits Manila Bay, there is no more arresting sight than a ruined concrete fort jutting out of the sea, with four big guns pointing seaward. Passengers of ships passing near the island usually gawk at the ruined fort, wondering what it is. In all my trips to Mindanao for the past three years, I have heard no one identifying the fort correctly.
The ruined concrete fortification (photos) is Fort Drum, formerly El Fraile Island, a concrete battleship, the only unsinkable battleship in the world, and one of the greatest military fortifications of all time. Fort Drum is a historic island and military fortification. It deserves to be promoted as a tourist spot, and its story is worth retelling.
Philippine defense became the United States’ responsibility when it annexed the country in 1898. As part of its defense plan for its new colony against future invaders, the US fortified four islands at the mouth of Manila Bay beginning in 1909, up to 1913. The four islands were Corregidor, Caballo, Carabao, and El Fraile, which became Fort Mills, Fort Hughes, Fort Frank, and Fort Drum, respectively.
According to War Plan Orange, the forts were to deny enemy warships from entering Manila Bay and to provide assistance in Bataan, where Filipino and American soldiers were to fight a delaying action for six months.
Of the forts, Corregidor was the biggest and most important; however, El Fraile or Fort Drum, the smallest, was the most unique. It was shaped like a battleship, complete with a forecastle. No wonder Fort Drum was also called USS Drum, because passengers of passing ocean liners often mistook it for a ship, albeit a strange one.
To build Fort Drum, the Corps of Engineers cut El Fraile, a small rocky island, to the mean water line, and, using the rock as foundation, erected a concrete fortification shaped like a battleship. The ”battleship” was 240 feet long, 160 feet wide, and 40 feet above the water line. The walls were thirty to forty feet thick and the deck twenty feet deep. Inside there were four levels connected by an axial tunnel running through the island.
Fort Drum bristled with eleven guns: Battery Wilson, a rotating turret with two fourteen-inch guns that can sink any known warship within twenty thousand yards; Battery Marshall, a rotating turret at the front, also with two fourteen-inchers; Battery Roberts, a casemated battery with four six-inch guns for minefield defense; and a battery of three three-inch guns, two of which were anti-aircraft guns.
In addition, Fort Drum had two eight-foot searchlights for night fighting. A garrison of 200 men were stationed at the fort. It took eleven years to construct Fort Drum, from 1909 to 1919. When it was completed, it was considered impregnable to all known armaments then, and impregnable it turned out to be.
War came to the Philippines with the bombing of Pearl Harbor in December of 1941. Fort Drum received its baptism of fire when Homma’s air force bombed Corregidor and its sister islands on 29 December 1941, and again on 2 through 6 January 1942.
Fort Drum was hardly nicked. Corregidor was heavily damaged, but not its guns, the anti-aircraft taking an appreciable toll on Japanese planes. The raids were costly and did not impair the fighting capabilities of the fortified islands. Thus, the Japanese stopped the bombing until later.
Beginning on 25 January, when the American troops were ensconced in Bataan, the Japanese began emplacing artillery pieces in Ternate on Cavite, to shell the island forts. The battery, commanded by Major Toshinori Kondo, commenced shelling on 5 February with four 105-mm guns and two 150-mm howitzers. The prime target on the first day was Fort Drum, which was hit a hundred times without effect.
From then on, Kondo’s fire on the four islands became regular. It intensified in mid-February, with the addition of two more 150-mm howitzers. The defenders responded with their big guns, but they were handicapped by lack of forward observers to give them the exact locations of Kondo’s guns. Only after Major Jess Villamor successfully took aerial photos of the Japanese batteries did they score direct hits. By late February, the fire from Kondo’s guns had diminished.
But, while Kondo’s fire was slackening, the Japanese were emplacing ten 240-mm howitzers in the Pico de Loro hills in Calumpang on Cavite, close to Fort Frank. This new artillery detachment under Major Masayoshi Hayakawa started unleashing deadly shells against the four islands on 15 March. Hayakawa’s shells, the deadliest in the Japanese arsenal, damaged most of Fort Frank’s guns. Fort Drum’s two searchlights and two anti-aircraft guns were destroyed, but not its fourteen-inch batteries, even though many shells landed on the top, sides, and face of the turrets. Fortunately, Hayakawa’s monsters were pulled out to Bataan on 22 March to join in the final assault of the peninsula. By then, Fort Drum was pock-marked with hits from Japanese shells which chipped at least four inches of concrete.
After Bataan surrendered on 9 April 1942, the Japanese began preparations for taking Corregidor and its sister islands. Starting on 11 April, the Japanese started shelling Corregidor, Fort Hughes, Fort Frank, and Fort Drum with more than a hundred guns, ranging from 75mm to 240mm. The guns of Corregidor, Fort Hughes, and Fort Frank countered as best they could, but it was an unequal artillery duel.
The Japanese not only had more guns, but also had observers on the ground and in the air with sensitive instrument for range-finding the islands’ batteries. Moreover, an average of fifty Japanese bombers had been bombing the islands since 24 March. The defenders could lob only a few salvoes before being plastered with Japanese shells. But the guns of Fort Drum were never silenced, affording the defenders much needed protection.
Japanese shellings and bombings intensified on 29 April, Emperor Hirohito’s birthday. To get rid of the pesky guns of Fort Drum, the Japanese subjected the fort to a glide-bombing attack which effected only a minor misalignment of Battery Marshall. The intense bombing-shelling continued for the next four days.
By 5 May, Corregidor’s guns had been silenced, except for one twelve-inch 1898 mortar of Battery Way and a few roving 155- and 75-mm guns which had not disclosed their positions. On the night of 5 May, the Japanese launched their two-battalion Corregidor invasion force. The gallant defenders destroyed two-thirds of the invaders, but the remainder made a successful beachhead with armor and three tanks. The defenders were outflanked, and reinforcements were immediately shelled by Japanese guns to keep them from containing the invaders. General Wainwright had no choice but to surrender Corregidor on 6 May 6. Through all this, Fort Drum’s guns continued to blaze until minutes before the surrender. 

The Americans returned on 20 October 1944 to begin the liberation of the Philippines. By 3 February 1945, a flying column had reached Manila, and a month-long battle liberating Manila from the Japanese ensued.  While the battle of Manila was raging, the Americans started clearing the fortified islands of Japanese to open Manila Bay for shipping. Fort Drum was the last to be liberated.
To liberate Fort Drum, which was impregnable to gunfire, the Americans devised special tactics. On 13 April (a Friday), a Landing Ship Medium (LSM) pulled up alongside Fort Drum and discharged two platoons of soldiers by means of a specially-built ramp on top of the LSM. One platoon consisted of snipers to cover every opening where Japanese soldiers might appear. The other platoon were engineers assigned to plant demolition charges.
When the charges were in place, a Landing Craft Mechanized (LCM) that had also sidled alongside the fort poured three thousand gallons of oil into one of the vents while explosives were dumped into another vent. The fuses were lit, and the LCM and LSM moved to a safe distance. The charges were detonated, resulting in a series of explosions that hurled Fort Drum’s one-ton, one-meter diameter manhole cover fifty meters straight up into the air.
It was not until 18 April that the Americans could enter the fort. They discovered over sixty charred bodies. Today, Fort Drum stands a ruined hulk in the mouth of Manila Bay, no longer defiant but still unsinkable. Sadly, Fort Drum and nearby Fort Frank are neglected as tourist spots.

Rico says it's another place he's not liable to visit...