Japan had been invading several small parts of the Philippines since 8 December 1941 and had seen almost no organized resistance by either the Americans stationed on the Philippines, or the Filipino army.
The Japanese first entered Naga on 17 December, coming from the recently captured Legaspi. There, they ran into an engineer battalion, sent out to destroy bridges and roads to slow the Japanese advance. Though not major, this marks one of the first successful attempts by ground forces in the Philippines to stop the Japanese advance. The battalion successfully destroyed the bridge, and set up a defensive position. The Japanese withdrew and came back the next day with more men.