SM UC-12 was a German Type UC I minelayer submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I.

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History
German Empire
Name	UC-12
Ordered	23 November 1914[1]
Builder	AG Weser, Bremen[2]
Yard number	226[1]
Laid down	27 January 1915[1]
Launched	29 April 1915[1]
Commissioned	2 May 1915[1]
Fate	Sunk by own mine, 16 March 1916[1]
General characteristics [3]
Class and type	German Type UC I submarine
Displacement	168 t (165 long tons), surfaced 182 t (179 long tons), submerged
Length	33.99 m (111 ft 6 in) o/a 29.62 m (97 ft 2 in) pressure hull
Beam	3.15 m (10 ft 4 in)
Draft	3.06 m (10 ft 0 in)
Propulsion	1 × propeller shaft 1 × 6-cylinder, 4-stroke diesel engine, 80 PS (59 kW; 79 bhp) 1 × electric motor, 175 PS (129 kW; 173 shp)
Speed	6.49 knots (12.02 km/h; 7.47 mph), surfaced 5.67 knots (10.50 km/h; 6.52 mph), submerged
Range	910 nmi (1,690 km; 1,050 mi) at 5 knots (9.3 km/h; 5.8 mph) surfaced 50 nmi (93 km; 58 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	50 m (160 ft)
Complement	14
Armament	6 × 100 cm (39 in) mine tubes 12 × UC 120 mines 1 × 8 mm (0.31 in) machine gun
Service record
Part of:	Pola Flotilla 27 June 1915 – 16 March 1916
Commanders:	Oblt.z.S. Cäsar Bauer[4] 2 May – 26 June 1915 Kptlt. Karl Palis[5] 27 June 1915 – 1 January 1916 Oblt.z.S. Eberhard Fröhner[6] 2 January – 16 March 1916
Operations:	7 patrols
Victories:	1 merchant ship sunk (2,382 GRT) 5 auxiliary warships sunk (907 GRT)

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A German Type UC I submarine, UC-1 had a displacement of 168 tonnes (165 long tons) when at the surface and 182 tonnes (179 long tons) while submerged. She had a length overall of 33.99 m (111 ft 6 in), a beam of 3.15 m (10 ft 4 in), and a draught of 3.06 m (10 ft). The submarine was powered by one Benz six-cylinder, four-stroke diesel engine producing 80 metric horsepower (59 kW; 79 shp), an electric motor producing 175 metric horsepower (129 kW; 173 shp), and one propeller shaft. She was capable of operating at a depth of 50 metres (160 ft).^[3]

The submarine had a maximum surface speed of 6.49 knots (12.02 km/h; 7.47 mph) and a maximum submerged speed of 5.67 knots (10.50 km/h; 6.52 mph). When submerged, she could operate for 50 nautical miles (93 km; 58 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 910 nautical miles (1,690 km; 1,050 mi) at 5 knots (9.3 km/h; 5.8 mph). UC-1 was fitted with six 100 centimetres (39 in) mine tubes, twelve UC 120 mines, and one 8 millimetres (0.31 in) machine gun. She was built by AG Weser Bremen and her complement was fourteen crew members.^[3]

The U-boat was ordered on 23 November 1914, laid down on 27 January 1915, and was launched on 29 April 1915. She was commissioned into the German Imperial Navy on 2 May 1915 as SM UC-12.^{[Note 1]}

UC-12 served with the Pola Flotilla based at Cattaro in the Adriatic. She operated as a minelayer, and undertook seven patrols in this role. Mines laid by UC-12 were credited with sinking six ships. One of these, the Italian Marechiaro sunk on 21 February 1916, was listed as a hospital ship and sank with over 200 casualties.^[7] Since Germany was not at war with Italy at this stage, though Austria was, UC 12, like other German U-boats in the Mediterranean, operated under the Austro-Hungarian flag.

On 16 March 1916 UC-12 was sunk by the detonation of one of her own mines while laying a mine fields off Taranto harbour. Italian divers inspected the wreck and established its identity. The knowledge that Germany, technically their ally, was assiduously mining their naval bases was a contributing factor in Italy’s decision in August 1916 to declare war on Germany.^[8] The submarine was raised by Italy and commissioned as X-1 in the Italian Royal Navy.^[1]