要塞砲
Caballo Island, with Fort Hughes—just south of Corregidor—was the next largest in area. At about , the island rose abruptly from the bay to a height of on its western side. Commander Francis J. Bridget was in charge of its beach defenses with a total of 800 men, of whom 93 were Marines and 443 belonged to the Navy, by the end of April 1942. Coastal artillery numbered some 13 assorted pieces, including a single 14-inch M1910 field gun, four 12-inch M1912 mortars, two 6-inch M1908 guns, and 2 3-inch M1903 guns, with its anti-aircraft defenses are tied in with those of Corregidor.