 "Sumter" completed landing all of her troops by 3 February and sailed the next day for the South Pacific for amphibious training.After exercises in New Caledonia and the Ellice and Solomon Islands, she returned to Pearl Harbor on 8 April.As a component of Task Group (TG) 54.4, Admiral R. K. Turner's Northern Attack Force for the invasion of Saipan and Tinian, the transport again loaded elements of the 4th Marine Division and sailed on 29 May.