USS Oyster Bay (AGP-6) late 1944 with PT boats alongside
At the end of March/first of April 1944, some 80 years ago, the fighting motor torpedo boat tender USS Oyster Bay (AGP-6), with the Elco-made 80-foot mosquito boats of MTBRon 18 and MTBRon 21 in tow, was pressed into service bombarding targets in the Admiralties with her 5-inch guns, softening the islands up for landings there by the Army’s 1st Cavalry Division (“First Team”). Likewise, her PT boats got into the act closer to “D” day, coming in close enough to run light mortars (81mm and 60mm) from their decks as well as 37mm and 20mm guns.
PT boats bombarding Pityilu Island, Seeadler Harbor, before landings there by the Army’s First Cavalry Division, on 30 March 1944. Note the large 37mm and 20mm guns on these boats. National Archives SC 189625
As detailed in At Close Quarters: PT Boats in the United States Navy, by Robert J. Bulkley, emphasis mine:
Pityilu Island had been bombed and strafed by aircraft and shelled by destroyers at intervals for more than 2 weeks before the landings on March 30. The Oyster Bay had been pressed into service on March 14 to knock out enemy positions on the island with 60 rounds from her 5-inch guns. On the morning of March 30, 10 PT’s got underway to support the landings. Joe Burk’s PT 320 dropped a marker buoy to guide the amphibious craft through a channel between two reefs. PT’s 324 and 326, patrolling the southeast tip of the island to prevent evacuation, quickly silenced light sniper fire with their guns. After the island had been shelled by destroyers and strafed by P-40’s and Spitfires, PT’s 320, 325, 328, 362, 363, 365, and 367 moved in ahead of the landing craft and mortared and strafed the beach. Machineguns fired inaccurately at the boats from shore. PT 331 (Lt. (jg.) Bernard A. Crimmins, USNR), with General Swift aboard, was used as an observation post for the high command in the immediate vicinity of the landing area. The troops met stiff resistance, but by nightfall had gained complete control of the island.
The following morning PT’s 362, 363, 365, 366, and 367 bombarded Koruniat Island with mortars, and Oyster Bay, with PT’s 320, 321, 325,
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and 326, shelled and strafed Ndrilo Island. On April 1 an Army combat team went ashore on Koruniat and later moved to Ndrilo. Both islands were deserted.