On the morning of 13 December, the British submarine , commanded by Lieutenant Norman Holbrook, entered the Dardanelles. At around 11:30, she spotted "Mesudiye" at anchor and fired a single torpedo from a distance of . The torpedo hit the ship's stern and caused serious damage; "Mesudiye"s guns briefly fired at "B11"s periscope before the ship capsized and sank in shallow water. Casualties were light, with only 10 officers and 27 enlisted men killed in the attack. A salvage effort removed the 150 mm and 76 mm guns, which were used to strengthen the defenses of the Dardanelles. In the meantime, "B11" successfully passed back through the Dardanelles and returned to port; Holbrook was awarded the Victoria Cross for sinking "Mesudiye".