Before long, the Pirate had swept five moored contact mines with her port gear and one with the starboard. A U.S. helicopter flying low across the harbor reported sighting a large "cabbage patch" of mines, but the pilot's report did not make clear its exact location relative to the sweeps. About the same time that the Pirate 's sonar began sounding a great many contacts, the bow lookout excitedly reported seeing a mine at shallow depth off the starboard bow. The Pirate 's skipper, Lieutenant Cornelius McMullen, immediately ordered hard left rudder to swing the ship's bow away and then rapidly followed with an order to shift the rudder to hard right, hoping to swing her stern clear.
But it was too late. A powerful explosion erupted on the starboard side. McMullen was initially knocked out but regained consciousness within half a minute. The Pirate was already listing heavily, and it was soon clear that she was not going to survive. McMullen ordered the lifeboats and floater nets deployed and then ordered "abandon ship." When he was certain that all hands had departed, McMullen went over the side as the ship's fantail settled into the water. Within four minutes, the Pirate was gone.
The enemy shore batteries now opened up and shrapnel-laden geysers erupted all about the Sailors in the water. The next ship in the column, the USS Pledge (AM-277), immediately began to move in to rescue the men from the cold water, but the shore batteries caused her to take evasive action, and then she, too, struck a mine. It was a fatal blow, and she would soon join the Pirate on the bottom of Wonsan Harbor.
Undaunted by the heavy fire from ashore and the probability of more mines, the destroyer Endicott (DMS-35) moved in to rescue the survivors of the sinking ships. Aided by a PBM Mariner aircraft, whose crew provided spotting information to the destroyer's gunners while strafing the North Koreans with their own machine guns, the Endicott recovered all but 13 of the stricken ships' crews.
Despite this rather intimidating precedent, other minesweeping Sailors followed in the Pirate 's wake and eventually were able to sweep a safe channel. Lieutenant McMullen was later awarded the Silver Star, and the Pirate received a Presidential Unit Citation.