SM U-81

SM U-81 was one of the 329 submarines serving in the Imperial German Navy (Kaiserliche Marine) in World War I. U-81 was engaged in the naval warfare and took part in the First Battle of the Atlantic.

U-81 had one 10.5 cm gun with 140-240 rounds. On 8 February 1917 she torpedoed the SS Mantola (1916) 143 miles off Fastnet, forcing her crew to abandon her. She then shelled the drifting hulk until being chased away by the Acacia-class sloop HMS Laburnum (1915). Laburnam took the floating hulk under tow, but the line parted in the rough seas, and Mantola was left to sink, which she did on 9 February.