SM U-73

	Willy Stöwer: sinking a troop transport by a German submarine in the Mediterranean, postcard from 1917 - missions such as U-73 offered motifs for marine painters
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 in position 44°52′N 13°50′E / 44.867°N 13.833°E
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 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 starboard stern); 4 torpedoes; 1 × 8.8 cm (3.5 in) SK L/30 deck guns;
Service record
Part of:	Pola / Mittelmeer / Mittelmeer II Flotilla; 30 April 1916 – 30 October 1918;
Commanders:	Kptlt. Gustav Sieß; 9 October 1915 – 21 May 1917; Kptlt. Ernst von Voigt; 22 May 1917 – 15 January 1918; Kptlt. Karl Meusel; 16 January – 15 June 1918; Oblt. Carl Bünte; 16 June – 15 September 1918 ; Kptlt. Fritz Saupe; 16 September – 30 October 1918;
Operations:	9 patrols
Victories:	13 merchant ships sunk ; (24,483 GRT); 3 warships sunk ; (28750 tons); 5 auxiliary warships sunk ; (62,366 GRT); 2 merchant ships damaged ; (1,749 GRT); 1 auxiliary warship damaged ; (6,318 GRT);

SM U-73 was one of 329

First Battle of the Atlantic. U-73 has the distinction of being responsible for planting the underwater mine that later led to the sinking of the largest ship sunk during World War I, the 48,158 tons hospital ship Britannic.^[8]

Operations

After completion at

Cattaro

on about 1 May (the date is uncertain), U-73 joined the Pola-Cattaro Flotilla.

The minelaying cruises of U-73 in the Mediterranean cannot be reconstructed. The battleship HMS Russell hit two of the mines and sank. On 7 October 1916 she is reported to have left

Gulf of Athens on which two Greek ships were blown up. It seems certain U-73, still commanded by Sieß,^[1] laid the mine by which the hospital ship HMHS Britannic (currently the largest passenger ship resting on the seafloor and the largest ship sunk during World War I) was lost, only one hour after U-73 laid the mine.^[11] It is possible the hospital ship HMHS Braemar Castle was also damaged by one of her mines. U-73 suffered from constant machinery trouble that was common with her class. At the end of October 1918, now in the hands of Kptlt. Fritz Saupe,^[1] she was scuttled

at Pola in Croatia.

Summary of raiding history

Date	Name	Nationality	Tonnage^{[Note 1]}	Fate^[12]
11 April 1916	Inverlyon	United Kingdom	1,827	Sunk
17 April 1916	Terje Viken	Norway	3,579	Sunk
27 April 1916	HMS Nasturtium	Royal Navy	1,250	Sunk
27 April 1916	HMS Russell	Royal Navy	14,000	Sunk
28 April 1916	HMY Aegusa	Royal Navy	1,242	Sunk
4 May 1916	HMT Crownsin	Royal Navy	137	Sunk
3 August 1916	HMS Clacton	Royal Navy	820	Sunk
9 August 1916	Lorenzo Donato	Italy	140	Sunk
24 October 1916	Propontis	Greece	700	Sunk
31 October 1916	Kiki Issaias	Greece	2,993	Sunk
14 November 1916	Burdigala	French Navy	12,009	Sunk
20 November 1916	Spetzai	Greece	788	Damaged
20 November 1916	Sparti	Greece	961	Damaged
21 November 1916	HMHS Britannic	Royal Navy	48,158	Sunk
23 November 1916	HMHS Braemar Castle	Royal Navy	6,318	Damaged
21 December 1916	Murex	United Kingdom	3,564	Sunk
23 December 1916	Thistleban	United Kingdom	4,117	Sunk
4 January 1917	Peresvyet	Imperial Russian Navy	13,500	Sunk
12 March 1917	Bilswood	United Kingdom	3,097	Sunk
29 September 1917	R 235	France	15	Sunk
30 September 1917	Midlothian	United Kingdom	1,321	Sunk
30 September 1917	Nicolosa	Greece	50	Sunk
1 October 1917	Ludovicos	United Kingdom	50	Sunk
19 October 1918	Almerian	United Kingdom	3,030	Sunk

References

Notes

gross register tons. Military vessels are listed by tons displacement
.

Citations

^ ^a ^b ^c ^d ^e Helgason, Guðmundur. "WWI U-boats: U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Gröner 1991, pp. 10–11.

^ Helgason, Guðmundur. "WWI U-boat commanders: Gustav Sieß". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Helgason, Guðmundur. "WWI U-boat commanders: Ernst von Voigt". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Helgason, Guðmundur. "WWI U-boat commanders: Karl Meusel". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Helgason, Guðmundur. "WWI U-boat commanders: Carl Bünte". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Helgason, Guðmundur. "WWI U-boat commanders: Fritz Saupe". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ Helgason, Guðmundur. "Ships hit during WWI: Britannic". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

^ National Archives, Kew: HW 7/3

^ "HMS Nasturtium (Flower Class Sloop - Arabis Type)". Subway Dive Centre. Archived from the original on 22 August 2014. Retrieved 29 August 2014.

^ Spencer, Carl. "Interview with Carl Spencer (Leader 2003 Britannic Expedition)". Hospital Ship Britannic. Archived from the original on 19 March 2018. Retrieved 4 February 2018.

^ Helgason, Guðmundur. "Ships hit by U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

Bibliography

Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press.
ISBN 0-85177-593-4
.

v
t
e
German Type UE I submarines

U-71

U-72

U-73

U-74

U-75

U-76

U-77

U-78

U-79

U-80

Preceded by: Type U 66

Followed by: Type U 81

List of U-boats of Germany

v
t
e
Shipwrecks and maritime incidents in October 1918
Shipwrecks

2 Oct: Keltier

3 Oct: Burutu, SMS G41

4 Oct: HMS L10, SM UB-68, Oceania

5 Oct: USS Mary Alice, SM UB-10, SM UB-40, SM UB-59, SM UC-4

6 Oct: HMS C12, HMS Otranto

7 Oct: USS West Gate

10 Oct: Leinster, Senator Schröder

15 Oct: HMS J6

16 Oct: Dumaru, SM UB-90

19 Oct: HMS Plumpton, SM UB-123

20 Oct: HMS M21

21 Oct: USS Cero, SM UB-89

23 Oct: HMS D1

25 Oct: Princess Sophia

27 Oct: SM U-78

28 Oct: USS Tarantula, SM U-47, SM U-65, SM UB-48, SM UB-116, SM UC-25, SM UC-53, SM UC-54

30 Oct: HMCS Galiano, SM U-73, SM UC-34

31 Oct: SM UB-129

Unknown date: SMS Brugge, HMS G7, SM U-34

Other incidents

2 Oct: Aquitania, USS Shaw

3 Oct: USS George G. Henry

5 Oct: USS O-13

6 Oct: HMS Kashmir

7 Oct: USS American

12 Oct: USAT Amphion

15 Oct: HMS Cymric

18 Oct: Voltaire

20 Oct: USS Berwyn

21 Oct: SMS Frankfurt

1917 1918 1919
September 1918 November 1918

Retrieved from "https://en.wikipedia.org/w/index.php?title=SM_U-73&oldid=1212123926"

[tonnage-12] ross register tons. Military vessels are listed by tons displacement
.

[U73-1] Helgason, Guðmundur. "WWI U-boats: U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[FOOTNOTEGröner199110–11-2] Gröner 1991, pp. 10–11.

[3] Helgason, Guðmundur. "WWI U-boat commanders: Gustav Sieß". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[4] Helgason, Guðmundur. "WWI U-boat commanders: Ernst von Voigt". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[5] Helgason, Guðmundur. "WWI U-boat commanders: Karl Meusel". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[6] Helgason, Guðmundur. "WWI U-boat commanders: Carl Bünte". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[7] Helgason, Guðmundur. "WWI U-boat commanders: Fritz Saupe". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[8] Helgason, Guðmundur. "Ships hit during WWI: Britannic". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

[9] National Archives, Kew: HW 7/3

[10] "HMS Nasturtium (Flower Class Sloop - Arabis Type)". Subway Dive Centre. Archived from the original on 22 August 2014. Retrieved 29 August 2014.

[11] Spencer, Carl. "Interview with Carl Spencer (Leader 2003 Britannic Expedition)". Hospital Ship Britannic. Archived from the original on 19 March 2018. Retrieved 4 February 2018.

[13] Helgason, Guðmundur. "Ships hit by U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.

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