On 18 April, "Long" sailed for the invasion of the Hollandia (currently known as Jayapura) area; she entered Humboldt Bay 22 April, made an exploratory sweep, and then fired a close-in preinvasion bombardment. "Long" arrived at Guadalcanal early in May to prepare for the Marianas assault, for which she sailed 4 June. Arriving Saipan 13 June for preinvasion sweeps west of the island, "Long" served as radar picket and guard ship until 24 June, then after a voyage to the Marshalls, screened the battleship during preinvasion bombardment of Guam beginning 12 July. After antisubmarine and convoy escort duty, "Long" joined TG 32.5 at Guadalcanal 16 August.