In the first few days after Pearl Harbor, all ROTC cadets were ordered to report for duty. There were about 14,000 of them who answered the call. However, due to the crying need for arms and materials with which to equip them, and the rapidity of the Japanese advance, the ROTCs were demobilized and disbanded. The demobilization order also affected the undergraduates of the Philippine Military Academy (PMA). Out of these two groups was born the Hunters ROTC guerrillas.