For the 4 islands in Manila Bay that used to be the Manila Bay Defense Forts, Corregidor-Ft. Mills, Caballo-Ft. Hughes, Fraile-Ft. Drum, Carabao-Ft.Frank.
Zf199. Japanese Report #30, the cover page, available in Corregidor.org. This picture came from Japanese archives found by the authors’ team of the book: Relentless Hope: A True Story of War and Survival, by David L. Britt