The American guerrillas who fought in Northern Luzon were escapees and evaders from Bataan, soldiers trapped in the region by the Japanese invading forces, or civilians displaced by the war from their engineering and lumbering work. Cut off from their Division/Company and practically on their own, these Americans sought refuge among friendly Filipinos in mountains and jungles, living off the land. From these groups emerged the leadership of guerrilla organizations that were eventually consolidated by Lt. Col. Russell W. Volckmann into the United States Armed Forces in the Philippines, Northern Luzon. These guerrillas engaged in ambushing and harassing the Japanese and in gathering intelligence which they sent via clandestine radio and submarines to Gen. Douglas MacArthur’s headquarters in Australia. Attacking the enemy involved ingenious methods and a lot of imagination and courage, considering the scarcity of weapons and Japanese reprisals against civilians.
As the mountainous terrain of Northern Luzon protected the guerrillas, it worked to the advantage of the Japanese as well. The American re-occupation of the Philippines drove the Japanese to retreat and hole up in the mountains of Northern Luzon, where it would be difficult for the American forces to extricate them. Such difficulty was expected to delay their defeat and to stall the eventual invasion of Japan. For these reasons, famous decisive battles in Balete Pass and Bessang Pass were fought in the region. The guerrillas—Americans and Filipinos—rendered and contributed valuable military and intelligence services in these battles that resulted in the final defeat of the Japanese in the Philippines, and the end of the war.