SM U-123 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-123 was engaged in the naval warfare and took part in the First Battle of the Atlantic. U-123 was surrendered to the Allies at Harwich on 22 November 1918 in accordance with the requirements of the Armistice with Germany. Initially earmarked for experiments, she was laid up at Portsmouth until towed out into the middle of the English Channel and scuttled on 28 June 1921.