After the Armistice with Germany, "O-5" operated out of the Submarine School at New London, Connecticut until 1923. "O-5" then sailed to Coco Solo, Panama Canal Zone, for a brief tour. On 28 October, as "O-5" entered Limon Bay, preparatory to transiting the Panama Canal, she was rammed by the United Fruit Company steamer "Abangarez" and sank in less than a minute. Three men died; 16 others escaped Two crewmembers, Henry Breault and Lawrence Brown, were trapped in the forward torpedo room, which they sealed against the flooding of the submarine. Local engineers and divers were able to rig cranes and other equipment and lift "O-5" far enough off the bottom that the bow broke the surface, exposing a hatch which led to the compartment where the two men were trapped, allowing them to be freed. Henry Breault was awarded the Medal of Honor for his actions.