At 1500 hours, the main offensive against Bataan defences at the Philippine Islands began, spearheaded by 6,500 men of the newly arrived and inexperienced 65th Infantry Brigade (which replaced the veteran Japanese 48th Division); the first attacks at the Abucay-Mauban defensive line were repelled by US-Filipino troops. Meanwhile, US Marines from Batteries A and C of 3rd Battalion, 4th Marine Regiment who remained on Bataan under naval control were integrated into a naval battalion for ground combat
