Military Wiki
SM UB-12
Career (German Empire)
Name: UB-12
Ordered: 15 October 1914[1]
Builder: AG Weser, Bremen[2]
Yard number: 221[1]
Laid down: 7 November 1914[1]
Launched: 2 March 1915[1]
Commissioned: 29 March 1915[1]
Fate: disappeared after 19 August 1918[1]
Service record
Part of:

German Imperial Navy[1]

  • Hans Nieland (Mar–Nov 1915)[1]
  • Wilhelm Kiel (Nov 1915 – Jun 1916)
  • Georg Gerth (Jun–Nov 1916)
  • Friedrich Moecke (Nov 1916 – Jan 1917)
  • Ernst Steindorff (Jan–Aug 1917)
  • Günther Wigankow (Aug–Sep 1917)
  • Wilhelm Braun (Sep 1917 – Mar 1918)
  • Nikolaus von Lyncker (Mar–May 1918)
  • Ernst Schöller (May–Aug 1918)
Operations: 36 patrols[1]
  • 22 ships (10,247 GRT) sunk[1]
  • 1 ship (665 GRT) captured as prize
  • 1 warship (995 tons displacement) sunk
General characteristics
Class & type: German Type UB I submarine
Displacement: 127 t (140 short tons), surfaced[2]
141 t (155 short tons), submerged
Length: 91 ft 6 in (27.89 m)[3]
Beam: 10 ft 6 in (3.20 m)[3]
Draft: 9 ft 10 in (3.00 m)[3]
Propulsion: 1 × propeller shaft
1 × Körting 4-cylinder diesel engine, 60 bhp (45 kW)[3]
1 × Siemens-Schuckert electric motor, 120 shp (89 kW)[3]
Speed: 7.45 knots (13.80 km/h), surfaced[2]
6.24 knots (11.56 km/h), submerged
Endurance: 1,500 nautical miles @ 5 knots, surfaced (2,800 km @ 9.3 km/h)[3]
45 nautical miles @ 4 knots, submerged (83 km @ 7.4 km/h)[3]
Test depth: 50 metres (160 ft)[3]
Complement: 14[3]
Armament: 2 × 45 cm (17.7 in) bow torpedo tubes[3]
2 × torpedoes
1 × 8 mm (0.31 in) machine gun
Notes: 33-second diving time[3]

SM UB-12 was a German Type UB I submarine or U-boat in the German Imperial Navy (German language: Kaiserliche Marine) during World War I. The submarine disappeared in August 1918.

UB-12 was ordered in October 1914 and was laid down at the AG Weser shipyard in Bremen in November. UB-12 was a little under 92 feet (28 m) in length and displaced between 127 and 141 metric tons (140 and 155 short tons), depending on whether surfaced or submerged. She carried two torpedoes for her two bow torpedo tubes and was also armed with a deck-mounted machine gun. UB-12 was broken into sections and shipped by rail to Antwerp for reassembly. She was launched and commissioned as SM UB-12 in March 1915.[Note 1]

UB-12 spent her entire career in the Flanders Flotilla and sank 22 merchant ships, about half of them British fishing vessels. The U-boat was also responsible for sinking the British destroyer HMS Laforey in 1917. By early 1917, UB-12 had been converted into a minelayer with the replacement of her torpedo tubes with four mine chutes. UB-12 disappeared after 19 August 1918.

Design and construction

After the German Army's rapid advance along the North Sea coast in the earliest stages of World War I, the German Imperial Navy found itself without suitable submarines that could be operated in the narrow and shallow seas off Flanders.[4][5] Project 34, a design effort begun in mid-August 1914,[5] produced the Type UB I design: a small submarine that could be shipped by rail to a port of operations and quickly assembled. Constrained by railroad size limitations, the UB I design called for a boat about 92 feet (28 m) long and displacing about 125 metric tons (138 short tons) with two torpedo tubes.[4][Note 2]

UB-12 was part of the initial allotment of seven submarines—numbered UB-9 to UB-15—ordered on 15 October from AG Weser of Bremen, just shy of two months after planning for the class began.[4][6] UB-12 was laid down by Weser in Bremen on 7 November.[1] As built, UB-12 was 91 feet 6 inches (27.89 m) long, 10 feet 6 inches (3.20 m) abeam, and had a draft of 9 feet 10 inches (3.00 m).[3] She had a single 60-brake-horsepower (45 kW) Körting 4-cylinder diesel engine for surface travel, and a single 120-shaft-horsepower (89 kW) Siemens-Schuckert electric motor for underwater travel, both attached to a single propeller shaft.[3] Her top speeds were 7.45 knots (13.80 km/h), surfaced, and 6.24 knots (11.56 km/h), submerged.[2] At more moderate speeds, she could sail up to 1,500 nautical miles (2,800 km) on the surface before refueling, and up to 45 nautical miles (83 km) submerged before recharging her batteries.[3] Like all boats of the class, UB-12 was rated to a diving depth of 50 metres (160 ft), and could completely submerge in 33 seconds.[3]

UB-12 was armed with two 45-centimeter (17.7 in) torpedoes in two bow torpedo tubes. She was also outfitted for a single 8-millimeter (0.31 in) machine gun on deck.[3] UB-12's standard complement consisted of one officer and thirteen enlisted men.[7]

After work on UB-12 was complete at the Weser yard, she was readied for rail shipment. The process of shipping a UB I boat involved breaking the submarine down into what was essentially a knock down kit. Each boat was broken into approximately fifteen pieces and loaded on to eight railway flatcars.[7] In February 1915, the sections of UB-12 were shipped to Antwerp for assembly in what was typically a two- to three-week process. After UB-12 was assembled and launched on 2 March,[1] she was loaded on a barge and taken through canals to Bruges where she underwent trials.[7]

Early career

The submarine was commissioned into the German Imperial Navy as SM UB-12 on 29 March 1915 under the command of Kapitänleutnant (Kapt.) Hans Nieland,[1] a 29-year-old first-time U-boat commander.[8][Note 3] On 18 April, UB-12 joined the Flanders Flotilla (German language: U-boote des Marinekorps U-Flotille Flandern),[1] which had been organized on 29 March.[7] When UB-12 joined the flotilla, Germany was in the midst of its first submarine offensive, begun in February. During this campaign, enemy vessels in the German-defined war zone (German language: Kriegsgebiet), which encompassed all waters around the United Kingdom, were to be sunk. Vessels of neutral countries were not to be attacked unless they definitively could be identified as enemy vessels operating under a false flag.[9]

The German war zone (German language: Kriegsgebiet) for the first submarine offensive.

On 24 July, Nieland and UB-12 sank four British fishing vessels while patrolling between 30 nautical miles (56 km) east-northeast of Lowestoft.[10][11] All four of the sunken ships were smacks—sailing vessels traditionally rigged with red ochre sails[12]—which were stopped, boarded by crewmen from UB-12, and sunk with explosives.[13] UB-12 similarly sank a pair of smacks off Lowestoft on 4 August,[13][14] and another trio from 23 to 25 August.[13][15]

On 21 November, Nieland was succeeded by Oberleutnant zur See (Oblt.) Wilhelm Kiel in command of UB-12.[16] Under Kiel's command, UB-12 sank three ships on 21 February 1916: the 100-ton Belgian fishing ship La Petite Henriette,[17] the largest sunk to-date by UB-12,[10] and another pair of British smacks, Oleander and W.E. Brown.[18]

UB-12 sank her largest ship, Silksworth Hall of 4,777 gross register tons (GRT), on 10 April. The British-registered ship was en route from Hull to Philadelphia in ballast when Kiel torpedoed her without warning a little more than one nautical mile (two kilometers) from the Corton Lightvessel.[19] Other ships picked up 31 survivors from Silksworth Hall, but 3 men were lost.[19][20] Later in the month, Admiral Reinhardt Scheer, the newest commander-in-chief of the High Seas Fleet, called off the merchant shipping offensive and ordered all boats at sea to return, and all boats in port to remain there.[21]

Grand Fleet ambush attempts

In mid-May, Scheer completed plans to draw out part of the British Grand Fleet.[22] The German High Seas Fleet would sortie for a raid on Sunderland,[23] luring the British fleet across "'nests' of submarines and mine-fields".[22] In support of the operation, UB-12 and five other Flanders boats set out at midnight 30/31 May to form a line 18 nautical miles (33 km) east of Lowestoft.[23][Note 4] This group was to intercept and attack the British light forces from Harwich, should they sortie north to join the battle.[23] Unfortunately for the Germans, the British Admiralty had intelligence reports of the departure of the submarines which, coupled with an absence of attacks on shipping, aroused British suspicions.[22]

A delayed departure of the German High Seas Fleet for its sortie (which had been redirected to the Skagerrak) and the failure of several of the U-boats stationed to the north to receive the coded message warning of the British advance caused Scheer's anticipated ambush to be a "complete and disappointing failure".[23] In UB-12's group, only UB-10 sighted the Harwich forces, and they were too far away to mount an attack.[23] The failure of the submarine ambush to sink any British capital ships allowed the full Grand Fleet to engage the numerically inferior High Seas Fleet in the Battle of Jutland, which took place 31 May – 1 June.[24]

About half of UB-12's 22 victims were fishing smacks, traditionally outiftted with red ochre sails, like this contemporary smack.[12]

Kapitänleutnant Georg Gerth took command of UB-12 on 26 June,[25] after Oblt. Kiel was assigned to command the new minelaying submarine UC-18.[16] Two months later, Admiral Scheer set up another ambush for the British fleet with plans for another High Seas Fleet raid on Sunderland (as had been the original intention in May). The German fleet planned to depart late in the day on 18 August and shell military targets the next morning. As in May, UB-12 was part of a group intended to attack the Harwich forces. As one of five boats forming the second line of boats from the Flanders Flotilla,[Note 5] UB-12 was stationed off Texel by the morning of 20 August.[26] Once again, British intelligence had given warning of the impending attack and ambush, causing the Grand Fleet to sortie at 16:00 on 18 August, five hours before the German fleet sailed. Faulty intelligence caused Scheer initially to divert from Sunderland, and then to eventually call off the whole operation. Although U-boats to the north sank two British light cruisers,[Note 6] UB-12 and her group played no part in the action.[26]

In September, Gerth led UB-12 in sinking two more ships and capturing a third ship as a prize. The 313-ton Norwegian steamer Rilda was sunk on 6 September,[27] while the 55-ton Marjorie was sunk on the 28th.[28] In between the Dutch ship Niobe was seized as a prize on the 7th.[29]

Conversion to minelayer

UB-12 and three sister boats—UB-10, UB-16, and UB-17—were all converted to minelaying submarines.[3] UB-12 was at the dockyard from November 1916 to January 1917,[30] and it is likely the boat was converted during this timeframe. The conversion involved removing the bow section containing the pair of torpedo tubes from each U-boat and replacing it with a new bow containing four mine chutes capable of carrying two mines each. In the process, the boats were lengthened to 105 feet (32 m), and the displacement increased to 147 metric tons (162 short tons) on the surface, and 161 metric tons (177 short tons) below the surface.[3]

During this same time, Kapt. Gerth was transferred to SM UC-61,[25] and replaced on UB-12 by Oblt. Friedrich Moecke in early November.[31] Moecke was, in turn, replaced by Oblt. Ernst Steindorff in January 1917.[32]

By March, the newly converted submarine had begun laying mines off the French coast. The French Navy trawler Elisabeth struck one of UB-12's mines off Calais on 13 March and sank.[33] Five days later, the British auxiliary minesweeper Duchess of Montrose sank with a loss of 12 men after detonating a mine laid by UB-12 off Gravelines.[34] On 23 March, HMS Laforey, a destroyer with the Dover Patrol, struck one of UB-12's mines off Cape Gris-Nez and went down with the loss of 59 men.[35]

In May, UB-12 was on a patrol with UB-39 in the English Channel.[36] On the night of 14/15 May while UB-12 was on the surface,[37] Steindorff noted a large underwater explosion some miles away in a British minefield, and when UB-39 failed to return to Zeebrugge, one of the bases for the Flanders Flotilla, reported what was likely the demise of UB-39 at the hands of a British mine.[38]

April found two more victims added to UB-12's tally. On the 20th, Nepaulin, another British auxiliary minesweeper was lost on one of UB-12's mines near the Dyck Lightvessel.[39] Six days later, the British steamer Alhama was mined while loaded with pit props destined for Dunkirk.[40] The 1,744-ton cargo ship was the largest ship sunk by UB-12 since the Silksworth Hall, sunk the previous April. UB-12 sank another two ships under Steindorff's command, one each in June and July.[10] The steamer Dulwich—carrying coal from Seaham for London—was mined and sunk with the loss of five men on 10 June.[41] One month later, the French patrol vessel Jupiter I was mined off Calais.[42] These were the last two ships credited to mines from UB-12 for the next fourteen months.[10]


UB-12's activities over the next year are not well documented, and no specific record of her can be found in English-language sources. However, it is known that during this period, she was helmed by four different commanders,[1] with the final officer, Oblt. Ernst Schöller, assuming command in May 1918.[43] Under Schöller's command, UB-12 departed Zeebrugge on 19 August to lay mines in the Downs off the Kentish coast, but never returned.[44] According to one British source, UB-12 was herself mined off Helgoland sometime in August.[45] Author Dwight Messimer considers this unlikely given that Helgoland is nowhere near the route that UB-12 could have taken to get to the Downs.[44] A postwar German study concluded the two most likely fates for UB-12 were that she either struck a British mine or was destroyed by one of her own mines that malfunctioned during deployment.[44] Messimer also considers it possible that UB-12 may have had a diving accident related to her conversion to a minelayer.[44]

Some two months after UB-12's presumed loss, she was credited with the sinking of her final ship.[10] On 27 October, two weeks before the end of the war, the 92-ton British ship Calceolaria struck one of UB-12's mines near the Elbow Lightvessel and sank.[46]

Ships sunk or damaged

Ships sunk or damaged by SM UB-12[10]
Date Name [Note 7] Tonnage Nationality
24 July 1915 Activity 56 British
24 July 1915 Henry Charles 41 British
24 July 1915 Kathleen 59 British
24 July 1915 Prosper 45 British
4 August 1915 Challenger 50 British
4 August 1915 Heliotrope 28 British
23 August 1915 Boy Bert 57 British
23 August 1915 Integrity 52 British
25 August 1915 Young Frank 49 British
21 February 1916 La Petite Henriette 100 Belgian
21 February 1916 Oleander 34 British
21 February 1916 W.E. Brown 34 British
10 April 1916 Silksworth Hall 4,777 British
6 September 1916 Rilda 313 Norwegian
7 September 1916 Niobe* 654 Dutch
28 September 1916 Marjorie 55 British
13 March 1917 Elisabeth 302 French
18 March 1917 PS Duchess of Montrose 322 British
23 March 1917 LaforeyHMS Laforey 995 British
20 April 1917 Nepaulin 314 British
26 April 1917 Alhama 1,744 British
10 June 1917 Dulwich 1,460 British
10 July 1917 Jupiter I 263 French
27 October 1918 Calceolaria 92 British
Total: 11,896

* captured as a prize


  1. "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
  2. A further refinement of the design—replacing the torpedo tubes with mine chutes but changing little else—evolved into the Type UC I coastal minelaying submarine. See: Miller, p. 458.
  3. Nieland was in the Navy's April 1905 cadet class with 36 other future U-boat captains, including Hermann von Fischel, Carl-Siegfried Ritter von Georg, Kurt Hartwig, Hans von Mellenthin, and Wilhelm Werner. See: Helgason, Guðmundur. "WWI Officer Crews: Crew 4/05". U-Boat War in World War I. Retrieved 30 March 2009. 
  4. The other five boats for the May action were UB-6, UB-10, UB-16, UB-17, and UB-29.
  5. The other four boats for the August action were UB-6, UB-16, UB-19, and UB-37.
  6. U-52 sank HMS Nottingham; U-66 and U-63 teamed up to sink HMS Falmouth.
  7. Merchant ship tonnages are in gross register tons. Military vessels are listed by tons displacement


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Helgason, Guðmundur. "WWI U-boats: UB-12". U-Boat War in World War I. Retrieved 19 February 2009. 
  2. 2.0 2.1 2.2 2.3 Tarrant, p. 172.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 Gardiner, p. 180.
  4. 4.0 4.1 4.2 Miller, pp. 46–47.
  5. 5.0 5.1 Karau, p. 48.
  6. Williamson, p. 12.
  7. 7.0 7.1 7.2 7.3 Karau, p. 49.
  8. Helgason, Guðmundur. "WWI U-boat commanders: Hans Nieland". U-Boat War in World War I. Retrieved 30 March 2009. 
  9. Tarrant, p. 14.
  10. 10.0 10.1 10.2 10.3 10.4 10.5 Helgason, Guðmundur. "Ships hit during WWI: Ships hit by UB 12". U-Boat War in World War I. Retrieved 30 March 2009. 
  11. Helgason, Guðmundur. "Ships hit during WWI: Activity", "Henry Charles", "Kathleen", "Prosper". U-Boat War in World War I. Retrieved 30 March 2009.
  12. 12.0 12.1 Penwith District Council (2009). "Boat Types". Penzance: Penwith District Council. Retrieved 30 March 2009. 
  13. 13.0 13.1 13.2 "British fishing vessels lost at sea due to enemy action: 1914, 1915, 1916 in date order". World War 1 at Sea. 9 January 2009. Retrieved 30 March 2009.  The information on the website is extracted from British Vessels Lost at Sea: 1914–1918. His Majesty's Stationary Office. 1919. 
  14. Helgason, Guðmundur. "Ships hit during WWI: Challenger", "Heliotrope". U-Boat War in World War I. Retrieved 30 March 2009.
  15. Helgason, Guðmundur. "Ships hit during WWI: Boy Bert", "Integrity", "Young Frank". U-Boat War in World War I. Retrieved 30 March 2009.
  16. 16.0 16.1 Helgason, Guðmundur. "WWI U-boat commanders: Wilhelm Kiel". U-Boat War in World War I. Retrieved 30 March 2009. 
  17. Helgason, Guðmundur. "Ships hit during WWI: La Petite Henriette". U-Boat War in World War I. Retrieved 30 March 2009. 
  18. Helgason, Guðmundur. "Ships hit during WWI: Oleander", "W.e. Brown". U-Boat War in World War I. Retrieved 30 March 2009.
  19. 19.0 19.1 Tennent, p. 175.
  20. "Spanish liner sunk". The Washington Post. 11 April 1916. p. 1. 
  21. Tarrant, p. 30.
  22. 22.0 22.1 22.2 Gibson and Prendergast, p. 97.
  23. 23.0 23.1 23.2 23.3 23.4 Tarrant, p. 32.
  24. Tarrant, pp. 32–33.
  25. 25.0 25.1 Helgason, Guðmundur. "WWI U-boat commanders: Georg Gerth". U-Boat War in World War I. Retrieved 30 March 2009. 
  26. 26.0 26.1 Tarrant, p. 33.
  27. Helgason, Guðmundur. "Ships hit during WWI: Rilda". U-Boat War in World War I. Retrieved 30 March 2009. 
  28. Helgason, Guðmundur. "Ships hit during WWI: Marjorie". U-Boat War in World War I. Retrieved 30 March 2009. 
  29. Helgason, Guðmundur. "Ships hit during WWI: Niobe (p.)". U-Boat War in World War I. Retrieved 30 March 2009. 
  30. Helgason, Guðmundur. "WWI U-boat commanders: Hans Ewald Niemer". U-Boat War in World War I. Retrieved 30 March 2009. 
  31. Helgason, Guðmundur. "WWI U-boat commanders: Friedrich Moecke". U-Boat War in World War I. Retrieved 30 March 2009. 
  32. Helgason, Guðmundur. "WWI U-boat commanders: Ernst Steindorff". U-Boat War in World War I. Retrieved 30 March 2009. 
  33. Helgason, Guðmundur. "Ships hit during WWI: Elisabeth". U-Boat War in World War I. Retrieved 30 March 2009. 
  34. Helgason, Guðmundur. "Ships hit during WWI: Duchess Of Montrose". U-Boat War in World War I. Retrieved 30 March 2009. 
  35. Helgason, Guðmundur. "Ships hit during WWI: Laforey (hms)". U-Boat War in World War I. Retrieved 30 March 2009. 
  36. Bridgland, p. 81.
  37. Messimer, p. 161.
  38. McCartney, p. 161.
  39. Helgason, Guðmundur. "Ships hit during WWI: Nepaulin". U-Boat War in World War I. Retrieved 30 March 2009. 
  40. Helgason, Guðmundur. "Ships hit during WWI: Alhama". U-Boat War in World War I. Retrieved 30 March 2009. 
  41. Helgason, Guðmundur. "Ships hit during WWI: Dulwich". U-Boat War in World War I. Retrieved 30 March 2009. 
  42. Helgason, Guðmundur. "Ships hit during WWI: Jupiter I". U-Boat War in World War I. Retrieved 30 March 2009. 
  43. Helgason, Guðmundur. "WWI U-boat commanders: Ernst Schöller". U-Boat War in World War I. Retrieved 30 March 2009. 
  44. 44.0 44.1 44.2 44.3 Messimer, p. 133
  45. Gibson and Prendergast, p. 318.
  46. Helgason, Guðmundur. "Ships hit during WWI: Calceolaria". U-Boat War in World War I. Retrieved 30 March 2009. 


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