called the "Guinea Pig Squadron". The "Guinea Pig Ships", sometimes called "ghost ships" due to their reduced crews, steamed the sea where mines had been laid to make certain that the explosives were no longer a menace to shipping. Of particular concern were pressure mines which, unlike magnetically- or acoustically-activated mines, were designed to detonate by a large change in the water pressure, such as that from the passage of an 8,000- to 10,000-ton ship. They were thus difficult to sweep. The US Navy laid many pressure mines in bays and sea ways of Japan, dropping many from Boeing B-29 Superfortress bombers. These mines had been designed to stop functioning over time, on schedule for a planned US invasion of Japan called Operation Downfall. The SS Pratt Victory swept for mines with two other damaged ships: the Liberty ship SS Joseph Holt which had taken damage from a grounding at Buckner Bay, Okinawa, in a typhoon and former troopship SS Marathon which had taken torpedo damage at Buckner Bay. The three ships steamed about apart in the sea ways near Japan. Pratt Victory was modified with remote controls for the engines and boilers so that no one had to be below deck, had empty cargo holds so she would float high in the water, and the decks and operation rooms of the ship were lined with mattresses. The crew was small, about 22 men, all volunteers for the dangerous assignment. All three ships completed their sweeps without detonating a mine; the US Navy minesweepers had cleared the sea way completely and many mines had stopped working as planned. The volunteer crew were awarded several medals: The Navy and Marine Corps Medal and the Bronze Star. Semon Leroy Teague, who served on the Pratt Victory, received the Bronze Star, with a citation that states: Post-war Pratt Victory was laid up in the James River in 1945, as part of the National Defense Reserve Fleet. She was repaired and put back in service as a new war started in the Far East. Korean War SS Pratt Victory served as merchant marine naval supplying goods for the Korean War. She helped to move the 140th Medium Tank Battalion. About 75 percent of the personnel and 90 percent of the cargo taken to the Korean War zone were delivered by merchant marine ships. SS Pratt Victory transported goods, mail, food and other supplies. SS