"Alshain" reached San Diego on 20 June but was ordered to replenish fuel and provisions and return to Hawaii. Upon her arrival at Pearl Harbor on the 28th, she was assigned to temporary Transport Division (TransDiv) 38 and began loading combat cargo and Army personnel scheduled to participate in the invasion of Guam. On 1 July, the vessel set sail for Eniwetok to join Task Force 51 as a part of the Southern Transport Group. The combined forces sortied from that atoll on 17 July and arrived off Agat Beach, Guam, on the 21st.