On September 11, 1966, the battalion command group moved to XT 637211. Company A conducted an S&D operation, destroying bunker and tunnel complexes. At 1205 hours two WIAs were sustained from small arms fire. At 1220 hrs a 105mm artillery round was command detonated against an APC wounding 3 Bobcats. Company B conducted an S&D operation, destroying bunkers and tunnel complexes and munitions. 3 APCs detonated mines with no casualties. At 1900 hours the battalion forward base received 4 rounds of 60mm mortar fire resulting in 1 Bobcat from Company A being killed. At 2005 hours Company B received 15 rounds of friendly 105mm artillery fire. 1 Bobcat from Company B was killed and 3 were seriously wounded. Supposedly someone was firing a counter-mortar barrage