SM U-78 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-78 was engaged in the naval warfare and took part in the First Battle of the Atlantic as a minelayer.

On 27 October 1918 low frequency communications from U-78 in the Skagerrak were detected by the British submarine HMS G2 which sank her with the loss of her crew of 40.

The following is a verbatim transcription of the recorded activities of SM U-78 known to British Naval Intelligence, Room 40 O.B.

Was completed at Hamburg (Vulcan) in May 1916, joined the Kiel School and remained there until the 8th of July, when she went to Wilhelmshaven, and was attached to the 1st Half Flotilla.

= around Scotland; Sound, Belts, Kattegat = via North of Denmark to/from German Baltic ports; Bight = to/from German North Sea ports; success = sinking of ships [9]