She was commissioned into the German Imperial Navy on 31 December 1917 as SM UB-109.

[Note 1] UB-109 was sunk by mine in the English Channel on 29 August 1918[2] and underwater scanning of the area covered by the Dover Barrage shows her wreck broken in half.

Like all Type UB III submarines, UB-109 carried 10 torpedoes and was armed with a 8.8 cm (3.46 in) deck gun.

UB-109 would carry a crew of up to 3 officer and 31 men and had a cruising range of 7,420 nautical miles (13,740 km; 8,540 mi).

Her engines enabled her to travel at 13.3 knots (24.6 km/h; 15.3 mph) when surfaced and 7.4 knots (13.7 km/h; 8.5 mph) when submerged.