U-1-class submarine (Austria-Hungary)

SM U-1, the class leader, in Pola.
Class overview
Builders	Pola Navy Yard, Pola
Operators	Austro-Hungarian Navy  State of Slovenes, Croats and Serbs Navy  Regia Marina
Succeeded by	U-3 class
Built	1907–1909
In commission	1911–1918
Planned	2
Completed	2
Scrapped	2
General characteristics (as built)
Type	submarine
Displacement	229.7 t (226 long tons) surfaced 248.9 t (245 long tons) submerged
Length	30.48 m (100 ft 0 in)
Beam	4.8 m (15 ft 9 in)
Draft	3.85 m (12 ft 8 in)
Propulsion	2 × shafts 2 × gasoline engines, 720 bhp (540 kW) total 2 × electric motors, 200 bhp (150 kW) total
Speed	10.3 knots (19.1 km/h; 11.9 mph) surfaced 6 knots (11 km/h; 6.9 mph) submerged
Range	950 nmi (1,760 km; 1,090 mi) at 6 knots (11 km/h; 6.9 mph), surfaced 40 nmi (74 km; 46 mi) at 2 knots (3.7 km/h; 2.3 mph), submerged
Test depth	40 meters (131 ft 3 in)
Complement	17
Armament	3 × 45 cm (17.7 in) torpedo tubes (two front, one rear); 5 torpedoes
General characteristics (after modernization)
Displacement	223.0 t (219 long tons) surfaced 277.5 t (273 long tons) submerged
Length	30.76 m (100 ft 11 in)
Propulsion	2 × shafts 2 × diesel engines, 720 bhp (540 kW) total 2 × electric motors, 200 bhp (150 kW) total
Armament	3 × 45 cm (17.7 in) torpedo tubes (two front, one rear); 5 torpedoes 1 × 37 mm (1.5 in) deck gun (installed in 1917, removed in January 1918)

The U-1 class (also called the Lake-type^[1]) was a class of two submarines or U-boats built for and operated by the Austro-Hungarian Navy (German: kaiserliche und königliche Kriegsmarine). The class comprised U-1 and U-2. The boats were built to an American design at the Pola Navy Yard after domestic design proposals failed to impress the Navy. Constructed between 1907 and 1909, the class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs.

Both U-1-class submarines were launched in 1909. An experimental design, the submarines included unique features such as a diving chamber and wheels for traveling along the seabed. Extensive sea trials were conducted in 1909 and 1910 to test these features as well as other components of the boats, including the diving tanks and engines for each boat. Safety and efficiency problems related to the gasoline engines of both submarines led the Navy to purchase new propulsion systems prior to World War I. The design of the U-1 class has been described by naval historians as a failure, being rendered obsolete by the time both submarines were commissioned into the Austro-Hungarian Navy in 1911. Despite this, tests of their design provided information that the Navy used to construct subsequent submarines. Both submarines of the U-1 class served as training boats through 1914, though they were mobilized briefly during the Balkan Wars.

At the outbreak of World War I, the U-1-class submarines were in drydock in Pola awaiting the installation of diesel engines. From 1915 to 1918, both boats conducted reconnaissance cruises out of Trieste and Pola, though neither sank any enemy vessels during the war. Declared obsolete in January 1918, both submarines were relegated to secondary duties and served as training boats at the Austro-Hungarian submarine base on Brioni Island, before being transferred back to Pola at the end of the war. When facing defeat in October 1918, the Austro-Hungarian government transferred its navy to the newly formed State of Slovenes, Croats and Serbs to avoid having to hand its ships over to the Allied Powers. Following the Armistice of Villa Giusti in November 1918, the U-1-class submarines were seized by Italian forces and subsequently granted to the Kingdom of Italy under the Treaty of Saint-Germain-en-Laye in 1920. Italy scrapped the submarines at Pola later that year.