Purchased by the U.S. Navy on 19 November 1940 for eventual conversion to a coastal minesweeper, she was commissioned as USS AMc-15 on 26 November 1940, and was named Waxbill the following day. Not yet fully equipped or manned, Waxbill operated in the 12th Naval District's waters, training naval reservists through to the end of 1940. Waxbill operated locally in the 12th Naval District attached, successively, to Patrol Force, Local Defense Forces and the Mine Force for the district until she was assigned to the Western Sea Frontier Force in August 1942.