In constructing the massive fortifications on the Manila Bay Fortified Islands the US Army made use of both civilian and convict labor. At the time such an arrangement was common practice in many U.S. States when it came to construction of public works. Convicts came from the Spanish era Bilibid Prison in downtown Manila. They were billeted at the Corregidor Stockade. Prisoners became known as “Bilibids”. All were Filipino Natives.
The Bilibids roamed the fortified islands performing construction and maintenance jobs. Philippine Scouts supervised. The Bilibid’s played a valuable and essential role in keeping the Manila Bay Forts operating. A 1937 article in the CAC-Journal covered their activities. -BB
(Source: US Army Coast Artillery Journal November- December 1937)