Located on El Fraile island off the shore of Manila Bay, it was more known to Americans and Filipino soldiers as the Island Battleship. Ít was part of the War Plan Orange, where 4 islands were to be fortified to defend Manila. Corregidor was the largest of these islands, and El Fraile was the smallest and the most unique. It took 11 years to complete, from 1909 to 1919.
It surrendered in 1942 to the Japanese army but remains to this day as the only unsinkable battleship in the world.
Question: What is its official name?