In the predawn hours of December 10, flares were observed in the skies north of Agana over Dungcas Beach, heralding the arrival of 400 sailors from the Japanese navy's 5th Defense Force to Guam. Knowing the Marine Barracks was several miles south of Agana, and not expecting much in the way of resistance, the Japanese sent an advance party to occupy Agana. During their approach, the Japanese party found and destroyed one machine-gun post before Agana. Here, to their surprise, the Guamanian Insular Guard, equipped with old M1903 rifles and another .30 caliber machine-gun had set up their defense.
