From 15–19 February 1944, "Montpelier" covered the amphibious landing on the Green Islands in the Bismarck Archipelago. In March, she hunted shipping south of Truk and participated in the invasion of the Emiraus. On 20 May 1944, "Montpelier" received light damage from return fire when she and two other light cruisers, along with eight destroyers, bombarded shore installations on Shortland, Poporang, and Magusaiai islands in the Shortlands. On 1 October 1944, the US Navy's Special Air Task Force (SATFOR), and began shelling Saipan on 14 June to support the Mariana Islands invasion. She joined TF 58 and participated in the decisive Battle of the Philippine Sea from 19–21 June. During the engagement, Japanese carrier air groups were virtually annihilated. "Montpelier" returned to the Marianas, and continued her shelling of Saipan, Tinian, and Guam. She left the Marianas on 2 August for overhauling in the United States.