SM U-73

History
German Empire
Name:	U-73
Ordered:	6 January 1915
Builder:	Kaiserliche Werft Danzig
Yard number:	29
Launched:	16 June 1915
Commissioned:	9 October 1915
Fate:	Scuttled during the evacuation of Cattaro 30 October 1918 i8n position 44°52′N 13°50′E / 44.867°N 13.833°E / 44.867; 13.833
General characteristics
Class and type:	German Type UE I submarine
Displacement:	745 t (733 long tons) surfaced 829 t (816 long tons) submerged
Length:	56.80 m (186 ft 4 in) (o/a) 46.66 m (153 ft 1 in) (pressure hull)
Beam:	5.90 m (19 ft 4 in) (o/a) 5.00 m (16 ft 5 in) (pressure hull)
Height:	8.25 m (27 ft 1 in)
Draught:	4.84 m (15 ft 11 in)
Installed power:	2 × 800 PS (588 kW; 789 shp) surfaced 2 × 800 PS (588 kW; 789 shp) submerged
Propulsion:	2 shafts, 2× 1.41 m (4 ft 8 in) propellers
Speed:	10.6 knots (19.6 km/h; 12.2 mph) surfaced 7.9 knots (14.6 km/h; 9.1 mph) submerged
Range:	7,880 nmi (14,590 km; 9,070 mi) at 7 knots (13 km/h; 8.1 mph) surfaced 83 nmi (154 km; 96 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth:	50 m (164 ft 1 in)
Complement:	4 officers, 28 enlisted
Armament:	2 × 50 cm (19.7 in) torpedo tubes (one starboard bow, one starbord stern) 4 torpedoes 1 × 8.8 cm (3.5 in) SK L/30 deck guns
Service record
Part of:	Imperial German Navy: Pola/Mittelmeer II Flotilla 30 April 1916 – 30 October 1918
Commanders:	Gustav Sieß 9 October 1915 – 21 May 1917 Ernst von Voigt 22 May 1917 – 15 January 1918 Karl Meusel 16 January – 15 June 1918 Carl Bünte 16 June – 14 July 1918 Fritz Saupe 15 July – 30 October 1918
Operations:	2 patrols
Victories:	18 ships sunk (87,449 GRT) 3 ships damaged (8,067 GRT) 3 warships sunk (28,750 GRT)

SM U-73 was one of 329 submarines serving in the Imperial German Navy in World War I. She engaged in the commerce war as part of the First Battle of the Atlantic.

U-73 has the distinction of being responsible for sinking the largest ship sunk in World War I, the 48,758 ton hospital ship Britannic, shortly after she laid the mine which Britannic struck.

After completion at Danzig in November 1915, U-73 was commissioned by Kapitänleutnant Gustav Sieß. She joined the Kiel School, where she remained until February 1916, conducting trials and crew training. She then left for the North Sea and was attached to the 1st Half Flotilla, still under Her activities were monitored throughout the war by Room 40, & most of her recorded movements are based on that information. Her first operational cruise began 1 April 1916, when she left Heligoland Bight, bound for the Mediterranean by way of the North Sea. En route, she attacked one steamer in the Atlantic and laid mines off Lisbon and Malta. On 27 April 1916 she laid a minefield of 22 mines outside the Grand Harbour of Valletta in which four ships were sunk: the battleship HMS Russell, the sloop Nasturtium; HMT Crownsin sunk 4 May 1916 with the loss of 11 men,[National Archives] [ Wreck.eu] and the yacht HMY Aegusa. On arriving Cattaro on about 1 May (the date is uncertain), U-73 joined the Pola-Cattaro Flotilla.

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