U-109 was a submarine in the Imperial German Navy (Kaiserliche Marine

Kaiserliche Marine

The Imperial German Navy was the German Navy created at the time of the formation of the German Empire. It existed between 1871 and 1919, growing out of the small Prussian Navy and Norddeutsche Bundesmarine, which primarily had the mission of coastal defense. Kaiser Wilhelm II greatly expanded...

) in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, taking part in the First Battle of the Atlantic. The building contract was confirmed 5 May 1916, and was awarded to Germaniawerft, Kiel. A Type 93 boat, she was launched 25 September 1917 and commissioned

Ship commissioning

Ship commissioning is the act or ceremony of placing a ship in active service, and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to the placing of a warship in active duty with its country's military...

 7 November. She was under the command of Otto Ney. On 28 January 1918, she was sunk in the English Channel, possibly by a mine

Naval mine

A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

, while diving to avoid ships from the Dover Patrol (particularly drifter

Drifter (fishing boat)

A drifter is a type of fishing boat. They were designed to catch herrings in a long drift net. Herring fishing using drifters has a long history in the Netherlands and in many British fishing ports, particularly in East Scottish ports....

H.M. Beryl III). She sank no ships.