The U.S. invasion plan was conceived in the hope of luring the Japanese into committing most of its forces to oppose the first landings on Red Beach and thereby allow the troops landing on Yellow Beach to attack from the rear. The Japanese, however, did not respond to the attack on Red Beach, and withdrew from Yellow Beach with only harassing fire, leaving the troops of the 27th Division no choice but to knock out the fortified strongpoints one by one. Reduction operations were hampered by the frequent inability to use heavy support weapons, including tanks, because of the danger of cross-fire. The commander of the 165th Infantry Regiment, Col. Gardiner Conroy, was killed in action by a Japanese sniper on the afternoon of the first day and was succeeded by Col. Gerard W. Kelley.