She was commissioned into the Flanders Flotilla of the German Imperial Navy on 19 July 1917 as SM UB-56.

[Note 1] She operated as part of the Flanders Flotilla based in Zeebrugge.

UB-56 was sunk at 23:41 on 19 December 1917 at 50°58′N 01°21′E / 50.967°N 1.350°E / 50.967; 1.350 after striking a mine, 37 crew members lost their lives in the event.

Like all Type UB III submarines, UB-56 carried 10 torpedoes and was armed with a 8.8 cm (3.46 in) deck gun.

UB-56 would carry a crew of up to 3 officer and 31 men and had a cruising range of 9,020 nautical miles (16,710 km; 10,380 mi).