During the Battle of Tarawa, the 6th Marines was the V Amphibious Corps' floating reserve. The assault waves stormed ashore on 20 November 1943 but ran into stiff opposition. Casualties were so heavy that the entire division reserve was committed on the first day. The 6th Marines was ordered ashore the following morning. The 1st and 3rd Battalions landed across Betio's Green Beach and were ordered to drive the length of the island, the 2nd Battalion was used as a blocking force on nearby Bairiki Island. Betio was declared secure after 76 bloody hours. The 1st and 3rd Battalions were re-located to a new rest camp in Hawaii, but the 2nd Battalion stayed on to clear the rest of the atoll. The 6th Marines suffered 355 casualties (99 dead, 256 wounded) and received a Presidential Unit Citation for its actions on Tarawa.