Military Wiki
UB-4 sometime in 1915
UB-4 sometime in 1915
Career (German Empire)
Name: UB-4
Ordered: 15 November 1914[1]
Builder: Germaniawerft, Kiel[2]
Yard number: 242[1]
Laid down: 3 November 1914[1]
Launched: March 1915[3]
Commissioned: 23 March 1915[1]
Fate: sunk by British Q-ship, 15 August 1915[1]
Service record
Part of:

German Imperial Navy

Operations: 14 patrols[1]
Victories: 4 ships sunk for a total of 10,942 GRT[1]
General characteristics
Class & type: German Type UB I submarine
Displacement: 127 t (140 short tons), surfaced[2]
142 t (157 short tons), submerged
Length: 92 ft 2 in (28.09 m)[4]
Beam: 10 ft 6 in (3.20 m)[4]
Draft: 9 ft 10 in (3.00 m)[4]
Propulsion: 1 × propeller shaft
1 × Daimler 4-cylinder diesel engine, 60 bhp (45 kW)[4]
1 × Siemens-Schuckert electric motor, 120 shp (89 kW)[4]
Speed: 6.47 knots (11.98 km/h), surfaced[2]
5.51 knots (10.20 km/h), submerged
Endurance: 1,650 nautical miles @ 5 knots, surfaced (3,060 km @ 9.3 km/h)[4]
45 nautical miles @ 4 knots, submerged (83 km @ 7.4 km/h)[4]
Test depth: 50 metres (160 ft)[4]
Complement: 14[4]
Armament: 2 × 45 cm (17.7 in) bow torpedo tubes[4]
2 × torpedoes
1 × 8 mm (0.31 in) machine gun
Notes: 33-second diving time[4]

Seiner Majestät[5] UB-4 was a German Type UB I submarine (U-boat) in the German Imperial Navy (German language: Kaiserliche Marine) during World War I. She was sunk by a British Q-ship disguised as a fishing smack in August 1915.

UB-4 was ordered in October 1914 and was laid down at the Germaniawerft shipyard in Kiel in November. UB-4 was a little more than 92 feet (28 m) in length and displaced between 127 and 142 metric tons (140 and 157 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-4 was broken into sections and shipped by rail to Antwerp for reassembly. She was launched and commissioned as SM UB-4 in March 1915.[Note 2]

UB-4 conducted the first sortie of the Flanders Flotilla in April, during which she sank the Belgian Relief ship Harpalyce, the first ship credited to the flotilla. She sank three more ships from mid-April to mid-August. On 15 August, UB-4 surfaced near the British Q-ship Inverlyon and was sunk by gunfire from the sailing vessel. None of UB-4's 14 crewmen survived the attack.

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 environment off Flanders.[6][7] Project 34, a design effort begun in mid-August 1914,[7] 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.[6][Note 3] UB-4 was part of the initial allotment of eight submarines—numbered UB-1 to UB-8—ordered on 15 October from Germaniawerft of Kiel, just shy of two months after planning for the class began.[6][8]

UB-4 was laid down by Germaniawerft in Kiel on 3 November.[1] As built, UB-4 was 92 feet 2 inches (28.09 m) long, 10 feet 6 inches (3.20 m) abeam, and had a draft of 9 feet 10 inches (3.00 m).[4] She had a single 60-brake-horsepower (45 kW) Daimler 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.[4] Her top speeds were 6.47 knots (11.98 km/h), surfaced, and 5.51 knots (10.20 km/h), submerged.[2] At more moderate speeds, she could sail up to 1,650 nautical miles (3,060 km) on the surface before refueling, and up to 45 nautical miles (83 km) submerged before recharging her batteries.[4] Like all boats of the class, UB-4 was rated to a diving depth of 50 metres (160 ft), and could completely submerge in 33 seconds.[4]

UB-4 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.[4] UB-4's standard complement consisted of one officer and thirteen enlisted men.[9]

After work on UB-4 was complete at the Germaniwerft yard, UB-4 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.[9] In early 1915, the sections of UB-4 were shipped to Antwerp for assembly in what was typically a two- to three-week process. After UB-4 was assembled and launched sometime in March,[3] she was loaded on a barge and taken through canals to Bruges where she underwent trials.[9]

Service career

The submarine was commissioned into the German Imperial Navy as SM UB-4 on 23 March under the command of Oberleutnant zur See Karl Gross,[1][Note 1] a 29-year-old first-time U-boat commander.[10][Note 4] UB-4 soon joined the other UB I boats then comprising the Flanders Flotilla (German language: U-boote des Marinekorps U-Flotille Flandern), which had been organized on 29 March.[9] When UB-4 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 (including the English Channel), 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.[11]

UB-4 kicked off operations for the new flotilla when she departed on her first patrol on 9 April. The following day, she sank the first ship credited to the Flanders Flotilla. The 5,940-ton British-flagged Harpalyce, which had been chartered by the American Commission for Relief in Belgium, was headed for Norfolk, Virginia, United States, in ballast after delivering relief supplies to Rotterdam.[12] UB-4 came upon the steamer between Harwich and the Hook of Holland and pulled to within about 100 yards (91 m).[13][14] Despite the fact that the ship had a pass of safe-conduct from Germany, was marked with the words "Belgian Relief" on her side, and was flying a white flag with the same wording, Gross torpedoed the vessel without warning.[13] Harpalyce sank in about five minutes, which allowed no time to launch any of the lifeboats. The Dutch steamers Elisabeth and Constance, and the American steamer Ruby picked up survivors. Herbert Hoover, head of the relief committee, reported that his organization's charter of the ship ended after delivery of the cargo in Rotterdam, but expressed disbelief that the ship could have been the victim of a torpedo attack, given the "distinct assurance" that ships engaged in the relief effort "would not be molested".[14] Harpalyce's master and 14 others from the 44-man crew died in the attack.[13] Harpalyce was the largest ship sunk by UB-4 during her career.[15]

UB-4's followed up the sinking of Harpalyce by sinking the Greek ship Ellispontos, a steamer of 2,989 gross register tons (GRT). Ellispontos was en route to Montevideo from Amsterdam when sunk by Gross and UB-4 on 17 April.[16] Although German U-boats sank over 100,000 tons of shipping in each of May and June,[17][18] UB-4 did not contribute to those totals.[15] She did add one ship to the 98,000-ton tally for July when she sank the Belgian ship Princesse Marie Jose and her load of coal on 29 July.[18][19] The 1,954-ton steamer had sailed from Dunston and was headed to Bordeaux when sunk 1.5 nautical miles (2.8 km) from the Shipwash Lightship off Harwich.[19]


Action of 15 August 1915
Part of World War I
U-boat Campaign
DateAugust 15, 1915
LocationOff the coast of Great Yarmouth, England
Result British victory
 Kaiserliche Marine  Royal Navy
Commanders and leaders
Karl Gross Ernest Martin Jehan
UB-4, 14 crewmembers Inverlyon, unknown number of crew
Casualties and losses
14 KIA, UB-4 sunk none

On 14 August, the 59-ton British fishing smack Bona Fide was stopped by a U-boat, boarded, and sunk with explosives 35 nautical miles (65 km) east-northeast of Lowestoft.[20] According to the website, this attack was likely by UB-4, because she was operating in the area on her fourteenth patrol.[21] Regardless of the identity of Bona Fide's attacker, UB-4 did approach a group of smacks in the vicinity the next day, but unbeknownst to UB-4's commander, Gross, one of the fishing vessels was actually a British decoy ship.[13][Note 5]

The decoy or Q-ship was His Majesty's Armed Smack Inverlyon, a smack that had been outfitted with a concealed 3-pounder (47 mm) gun. Around 20:20, UB-4 drew within 30 yards (27 m) of Inverlyon and Gross, on the conning tower of UB-4, shouted out commands to Inverlyon's crew in German. After waiting until the right moment, Ernest Jehan, a Royal Navy gunner in command of Inverlyon, ordered the White Ensign raised and gave the command to open fire. A burst of three rounds from the 3-pounder scored hits on the conning tower, the second destroying part of the bridge and sending Gross into the water. UB-4, with no one at the helm, drifted behind Inverlyon, and when clear, the 3-pounder fired another six shots into the hull of UB-4 at point blank range. All the while small arms fire from Inverlyon's crew peppered the submarine. The U-boat began going down by the bow, becoming nearly vertical before disappearing below the surface. A member of Inverlyon's crew attempted the rescue of one crewman from UB-4, but was unable to reach him before he went under, meeting the same fate as the other thirteen crewmen.[13]

As UB-4 went down, her hulk fouled the Inverlyon's nets—which had been deployed to keep up the appearance of a real fishing boat—essentially anchoring Inverlyon in place. The Q-ship's crew, not having a wireless set on board, sent word of the encounter with another smack, and followed up by releasing messenger pigeons the following morning, requesting instructions on what to do with UB-4. The thought of salvaging the snagged U-boat was rejected, so the nets were cut, freeing UB-4 to sink to the bottom.[13] UB-4's wreck lies at position 52°43′N 2°18′E / 52.717°N 2.3°E / 52.717; 2.3Coordinates: 52°43′N 2°18′E / 52.717°N 2.3°E / 52.717; 2.3.[22] Jehan was awarded the Distinguished Service Cross for the sinking of UB-4, and the crewmen of Inverlyon split the submarine bounty paid by the Admiralty.[13][Note 6]

Ships sunk or damaged

Ships sunk or damaged by SM UB-4[15]
Date Name [Note 7] Tonnage Nationality
Apr 10, 1915 HarpalyceHarpalyce 5,940 British
Apr 17, 1915 Ellispontos 2,989 Greek
Jul 29, 1915 Princesse Marie Jose 1,954 Belgian
Aug 14, 1915 Bona Fide 59 British


  1. 1.0 1.1 Karl Gross' name is also spelled as Karl Groß in some sources.
  2. "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
  3. 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.
  4. Gross 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, and Hans von Mellenthin. See: Helgason, Guðmundur. "WWI Officer Crews: Crew 4/05". U-Boat War in World War I. Retrieved 5 March 2009. 
  5. Perkins reports the date of the encounter as Sunday, 16 August 1915, but 16 August 1915 was actually a Monday. Messimer (p. 129), Gibson and Prendergast (pp. 50–51), and (WWI U-boats: UB-4) all report the date of the encounter as 15 August 1915.
  6. There is no mention of the amount of the bounty for sinking UB-4, but the Admiralty bounties were typically £5 per crewman on the submarine, or £70 in the case of UB-4. See: Messimer, pp. 158, 170, 222, for examples of the £5 per capita bounty.
  7. Tonnages are in gross register tons


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Helgason, Guðmundur. "WWI U-boats: UB-4". U-Boat War in World War I. Retrieved 19 February 2009. 
  2. 2.0 2.1 2.2 2.3 Tarrant, p. 172.
  3. 3.0 3.1 "UB-4 (6104975)". Miramar Ship Index. Retrieved 5 March 2009.  (subscription required)
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 Gardiner, p. 180.
  5. German: "His Majesty's"
  6. 6.0 6.1 6.2 Miller, pp. 46–47.
  7. 7.0 7.1 Karau, p. 48.
  8. Williamson, p. 12.
  9. 9.0 9.1 9.2 9.3 Karau, p. 49.
  10. Helgason, Guðmundur. "WWI U-boat commanders: Karl Groß". U-Boat War in World War I. Retrieved 5 March 2009. 
  11. Tarrant, p. 14.
  12. Helgason, Guðmundur. "Ships hit during WWI: Harpalyce". U-Boat War in World War I. Retrieved 5 March 2009. 
  13. 13.0 13.1 13.2 13.3 13.4 13.5 13.6 Perkins, Hugh (September 2008). "The gunner and the U-boat". Canoga Park, California: Challenge Publications. OCLC 60621086.;col1. Retrieved 5 March 2009. [dead link]
  14. 14.0 14.1 "Relief flag flying as Harpalyce sunk" (PDF). The New York Times. 12 April 1915. Retrieved 5 March 2009. 
  15. 15.0 15.1 15.2 Helgason, Guðmundur. "Ships hit during WWI: Ships hit by UB 4". U-Boat War in World War I. Retrieved 5 March 2009. 
  16. Helgason, Guðmundur. "Ships hit during WWI: Ellispontos". U-Boat War in World War I. Retrieved 5 March 2009. 
  17. Tarrant, p. 18.
  18. 18.0 18.1 Tarrant, p. 21.
  19. 19.0 19.1 Helgason, Guðmundur. "Ships hit during WWI: Princesse Marie Jose". U-Boat War in World War I. Retrieved 5 March 2009. 
  20. "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 5 March 2009.  The information on the website is extracted from British Vessels Lost at Sea: 1914–1918. His Majesty's Stationary Office. 1919. 
  21. Helgason, Guðmundur. "Ships hit during WWI: Bona Fide". U-Boat War in World War I. Retrieved 5 March 2009. 
  22. Messimer, p. 129


  • Gardiner, Robert, ed. (1985). Conway's All the World's Fighting Ships, 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 978-0-87021-907-8. OCLC 12119866. 
  • Gibson, R. H.; Maurice Prendergast (2003) [1931]. The German Submarine War, 1914–1918. Annapolis, Maryland: Naval Institute Press. ISBN 9781591143147. OCLC 52924732. 
  • Karau, Mark D. (2003). Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger. ISBN 978-0-313-32475-8. OCLC 51204317. 
  • Messimer, Dwight R. (2002). Verschollen: World War I U-boat losses. Annapolis, Maryland: Naval Institute Press. ISBN 978-1-55750-475-3. OCLC 231973419. 
  • Miller, David (2002). The Illustrated Directory of Submarines of the World. St. Paul, Minnesota: MBI Pub. Co. ISBN 978-0-7603-1345-9. OCLC 50208951. 
  • Tarrant, V. E. (1989). The U-Boat Offensive: 1914–1945. Annapolis, Maryland: Naval Institute Press. ISBN 978-0-87021-764-7. OCLC 20338385. 
  • Williamson, Gordon (2002). U-boats of the Kaiser's Navy. Oxford: Osprey. ISBN 978-1-84176-362-0. OCLC 48627495. 

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