Upon returning to the western Caroline Islands on 23 February 1945, the "Lassen", along with her sister ammunition ships, worked out techniques for transferring large quantities of ammunition to warships while underway at sea. The "Lassen" exhibited this new ability and mobility by accompanying aircraft carrier Task Group 50.8 in raids from 13 March to 14 June 1945, while supporting the conquest of Okinawa campaign. The "Lassen"s third battle star was earned while accompanying carrier Task Group 30.8 from 8 July to 6 August off the coasts of Japan itself.