In late afternoon of 12 May, from the cape, she encountered a merchantman and a trawler escort. For the first time, the weather, her position, and the target's course were all in her favor. She launched four torpedoes while surfaced and hit with two. She then submerged. "Shoei Maru", a salvage vessel of over 5,000 tons was sunk. The Japanese escort attacked "S-44" and dropped sixteen or more depth charges, none of which was close. On 14 May, "S-44" headed home, arriving at Brisbane on 23 May.