High Quality Content by WIKIPEDIA articles! USS PGM-18 was a PGM-9-class gunboat built for the United States Navy during World War II. She was built and originally commissioned as USS PC-1255, a PC-461-class submarine chaser, and was decommissioned and converted in late 1944. USS PGM-18 struck a mine off the coast of Okinawa in April 1945; 13 men lost their lives when PGM-18 sank.