"Twining" arrived at Pearl Harbor on the 17th to begin three months of training exercises, maneuvers, and drills, as her crew honed its skills in bombardment, fire support, and amphibious landing operations in preparation for Operation Forager. On 31 May, the destroyer departed the Hawaiian Islands in company with Fire Support Group 1 of the Saipan invasion forces. She arrived at Kwajalein on 8 June, fueled, and commenced antisubmarine patrols off the harbor entrance. On the 10th, "Twining" screened the sortie of the task group from the lagoon; headed for the Marianas; and arrived off Saipan at dawn on the 14th. Steaming off the island's eastern shore, she screened cruiser ; joined briefly in the pre-assault bombardment and, late in the afternoon, engaged in a running battle with a coastal battery. Leading and "Montpelier", "Twining" closed the shore to 3,000 yards and joined in the fire which silenced the enemy guns. As darkness fell, she took up her station to screen vessels supplying night harassment fire at Garapan on Saipan's west coast.