The Chinese offensive began on the night of March 26 against outposts Vegas, Carson, and Reno, in conjunction with attacking nearby outposts Dagmar, Esther, Bunker, and Rudy (Kudy?).
[2] At 19:00, small arms and machine gun fire erupted from the Chinese positions on the 1st Battalion, 5th Marines positions.
[3]:17 This was followed by 15 minutes of mortar and artillery fire on the 5th Marines rear areas and supply routes along the MLR. At 19:10, over 3,500 Chinese soldiers from the 358th Regiment, 120th Division, 46th PVA attacked ouposts Carson, Reno, and Vegas. One of the Chinese companies engaged the Marines atop outpost Vegas. Marine artillery responded to the Chinese attacks by firing "protective boxes" and
VT proximity fuses around the outposts and routes of attack.
[4]:281 When VT was fired at Chinese soldiers who were very close to the Marine positions – as was often the case – the Marines would run into previously dug caves on the opposite slope of the hills. There they would wait until the overwhelming numbers of Chinese soldiers were pushed off the hill by the VT shells, and then the Marines would reemerge from the caves to man the defenses. Overwhelming Chinese numbers and supporting fire forced the Marines on Vegas to abandon the outer ring of less easily defended trenches.
At the same time during the evening of the 26th, Marine tanks and artillery had been positioned on the MLR to support an infantry raid to destroy Chinese bunkers scheduled for the next morning on the 27th, designated "Operation Clambake." It was pure chance that they were positioned there just as the Chinese launched an attack in the same front.