Fort Hughes (Caballo Island, the Philippines) was part of the harbor defenses of Manila and Subic Bays built by the Philippine Department of the U.S. Army in the early 1900s. It was occupied by Japanese forces after their conquest of the Philippines. American forces retook the fort from the Japanese during the liberation of the Philippines in 1945. The American troops pumped two parts diesel oil and one part gasoline into the mortar pits, stood off, and ignited mixture with tracer bullets.