Haddocks second war patrol, commencing 11 October from Midway, was carried out in the Yellow Sea. After two attacks without hits, the submarine torpedoed Tekkai Maru (1925 tons) amidships on 3 November, breaking her in two. She was forced to break off another attack on 6 November after damaging the IJA converted troop transport French Maru (5828 tons) because of destroyers and search aircraft, but during the night of 11–12 November blew off the stern of cargo ship Venice Maru (6571 tons) east of the island of Honshū. Haddock damaged another ship on Friday 13 November, only to be prevented from finishing her off by escort craft, and she expended her last torpedo on Nichinan Maru (6503 tons) on 16 November. After a brief gunfire duel with her victim, (the merchantman sunk later that day.) the submarine headed for Pearl Harbor, arriving on 4 December.
