The Japanese Agat command had prepared its defenses well with thick-walled bunkers and smaller pillboxes. The 75mm guns on Gaan Point were in the middle of the landing beaches. Crossfire from Gaan coordinated with the machine guns on nearby tiny Yona island to rake the beaches allocated to the 4th Marines under Lieutenant Colonel Alan Shapley. The 4th Marines was to establish its beachhead, and protect the right or southernmost flank. After bitter fighting, the 4th Marines forged ahead on the low ground to its front and cleared Bangi Point where bunker walls could withstand a round from a battleship. Lieutenant Colonel Shapley set up a block on what was to be known as Harmon Road leading down from the mountains to Agat. A lesson well learned in previous operations was that the Japanese would be back in strength and at night.
_In quick order, the 105mm howitzers of LtCol Alpha L. Bowser’s 3d Battalion, 12th Marines, were landed and set up in camouflaged positions to support the attack._]
When the Marines landed, they found an excellent but undermanned Japanese trench system on the beaches, and while the pre-landing bombardment had driven enemy defenders back into their holes, they nonetheless were able to pour heavy machine gun and mortar fire down on the invaders. Pre-landing planning called for the Marine amtracs to drive 1,000 yards inland before discharging their embarked Marines, but this tactic failed because of a heavily mined beachhead, with its antitank ditches and other obstacles. However, the brigade attack ashore was so heavy, with overwhelming force the Marines were able to break through, and by 1034, the assault forces were 1,000 yards inland, and the 4th Marines’ reserve battalion had landed. After receiving extremely heavy fire from all emplaced Japanese forces, the Marines worked on cleaning out bypassed bunkers together with the now-landed tanks. By 1330, the Gaan Point blockhouse had been eliminated by taking the position from the rear and blasting the surprised enemy gunners before they could offer effective resistance. At this time also, the brigade command group was on the beach and General Shepherd had opened his command post.
TAKEN FROM A SCHEMATIC SKETCH DRAWN BY MAJOR HENRY APLINGTON, II]