USS Pioneer ( AM - 105 ) USS " Pioneer " ( AM - 105 ) was an acquired by the United States Navy for the dangerous task of removing mines from minefields laid in the water to prevent ships from passing . " Pioneer " was a U . S . Navy oceangoing minesweeper , named after the word " pioneer , " which is defined as a person or group that originates or helps open up a new line of thought or activity or a new method or technical development . " Pioneer " was laid down 30 October 1941 by Pennsylvania Shipyards , Inc . , Beaumont , Texas ; launched 26 July 1942 ; sponsored by Mrs . H . R . Jessup ; and commissioned 27 February 1943 , Lt . Comdr . H . B . Stevens in command . Convoy assignment . " Pioneer " trained her crew and experimented with newly developed gear in the Gulf of Mexico , Chesapeake Bay , and the Potomac River before joining a Mediterranean - bound convoy at New York on 14 May 1943 , for the first of four escort voyages from New York or Norfolk , Virginia , to North Africa n ports . In November she took up patrol and escort duty within the Mediterranean . On 26 November 1943 , while bound east from Oran , " Pioneer ' s " convoy was attacked by German bombers . They hit a British troopship ( with over 2 , 000 US servicemen aboard ) and set her afire ; " Pioneer " stood by , continuing to fire on the attacking aircraft while conducting the rescue of 606 soldiers and crewmen from " Rohna " . The ship ( with its crew of roughly 100 sailors ) , however , was never given any recognition for the rescue of over 600 HMT " Rohna " survivors . To this day ( June , 2007 ) , The Rohna Survivors Organization continues to try to have the " Pioneer " recognized for this extraordinary rescue operation . Operations in the invasion of Italy . She protected critically important Allied convoys in the Mediterranean until assigned to the assault force for the Anzio operation early in January 1944 . After training at Salerno , her group sortied from Naples on 21 January to sweep a mile - wide channel into the fire support and transport areas , and then swept these areas themselves . When the transports entered the newly cleared area , " Pioneer " began antisubmarine and antiaircraft patrol , and then resumed escort duties , bringing reinforcements to Anzio on 24 January . Desperate German resistance by land and air as well as from the sea prevented a breakout from Anzio . " Pioneer " guarded the beleaguered beachhead , patrolling to seaward , escorting supply and reinforcement movements , and sweeping mines dropped by enemy planes intent on isolating the beachhead by sea as it was by land . She returned to wider - ranging escort assignments when advancing Allied land forces broke through to Anzio late in May . Operations in invasion of France . On 12 August , " Pioneer " sortied for the invasion of southern France . Again minesweepers led the way , clearing the assault area , ignoring shore battery attacks while completing their complex and vital task . Patrol and sweeping operations included extensive activity to prepare newly captured Marseille to receive shipping . World War II Pacific operations . " Pioneer " sailed from Bizerte on 24 November for stateside overhaul preparatory to $ 3 deployment , for which she left Norfolk , Virginia , 15 February 1945 , bound for Panama en route to Hawaii . Arriving Pearl Harbor on 18 March after underway training , " Pioneer " installed new radar gear and joined in exercises before getting underway for Okinawa on 23 May . Calls en route delayed her arrival until 7 August . For the remainder of the year , " Pioneer " joined in the gigantic task of clearing Japanese and Chinese waters of the thousands of mines laid in a decade of warfare . Decommissioning and sale . Peaceful use of the oceans restored , " Pioneer " returned to San Pedro , California , 14 February 1946 to inactivate . She decommissioned and went into reserve at San Diego , California , 8 July 1946 . She was redesignated MSF - 105 on 7 February 1955 . Struck from the Navy Register on 1 July 1972 , the ship was sold to Mexico on 19 September 1972 . Awards . " Pioneer " received 4 battle stars for World War II service . Mexican Navy service . On 19 September 1972 , the former " Pioneer " was sold to the Mexican Navy and became ARM " Leandro Valle " ( C70 ) , the lead ship of the Mexican Navy ' s of offshore patrol vessel s . Her pennant number was later changed to G01 , and in 1993 , was changed for the final time to P101 . " Leandro Valle " was retired from service by 2004 . According to divers on a trip to Mexico , the ship was sunk by the Mexican navy in June 2006 .