A guerrilla resistance movement was already in its planning stage even before the bombing of Pearl Harbor on December 7, 1941. The Partido Komunista ng Pilipinas (PKP), founded in 1930, was getting ready for war at the same time that the United States Armed Forces in the Far East (USAFFE) was
rushing its war preparations that year. In October 1941, the PKP established a coordinating center in San Fernando, Pampanga for guerrilla activities.
In March 1942, Felipa Culala alias Kumander Dayang-Dayang organized a successful rescue operation for eight guerrillas who had been arrested and jailed by the Japanese in Candaba, Pampanga. Inspired by the battles won by Dayang-Dayang’s troops in Pampanga, the PKP convened in Nueva Ecija later that month to form the Hukbong Bayan Laban sa Hapon (HUKBALAHAP). Culala was elected as one of the four members of the Military Committee of the HUKBALAHAP, heading the Division of General Affairs which handled supplies and maintenance. She was the only woman in the group. Later she was accused of theft and abuse of power, leading to her execution at the firing squad by the Huk leaders in 1943.
Celia Mariano, a former school teacher and examiner at the Bureau of Civil Service, joined the PKP just before the war broke out in 1941. She and her comrades organized her parents’ farm in Tanay, Rizal as a base for guerrilla activities. She was then assigned by the Party as educator of guerrillas and villagers in Bulacan and Nueva Ecija, and she subsequently served as the editor of Katubusan ng Bayan, the revolutionary newspaper. Later, as education secretary, she supervised the Huk committees in Bulacan, Nueva Ecija, Pampanga, Tarlac, and Pangasinan. Among her students was Remedios Gomez, alias Kumander Liwayway.
Mariano continued to work in the underground movement after the Liberation until she and her husband were captured by government forces in 1952. By that time, the Huk had been reconstituted as the armed wing of the Party and renamed Hukbong Mapagpalaya ng Bayan (HMB).