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SM UB-68
SM UB-68
SM UB-68
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History
German Empire
NameUB-68
Ordered20 May 1916[1][2]
BuilderFriedrich Krupp Germaniawerft, Kiel
Cost3,276,000 German Papiermark
Yard number286
Launched4 July 1917[3]
Commissioned5 October 1917[3]
FateSunk 4 October 1918[3]
General characteristics [3]
Class & typeType UB III submarine
Displacement
  • 513 t (505 long tons) surfaced
  • 647 t (637 long tons) submerged
Length55.83 m (183 ft 2 in) (o/a)
Beam5.80 m (19 ft)
Draught3.67 m (12 ft 0 in)
Propulsion
Speed
  • 13.2 knots (24.4 km/h; 15.2 mph) surfaced
  • 7.6 knots (14.1 km/h; 8.7 mph) submerged
Range
  • 9,090 nmi (16,830 km; 10,460 mi) at 6 knots (11 km/h; 6.9 mph) surfaced
  • 55 nmi (102 km; 63 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth50 m (160 ft)
Complement3 officers, 31 men[3]
Armament
Notes30-second diving time
Service record
Part of:
  • Mittelmeer I Flotilla[2]
  • 8 January – 4 October 1918
Commanders:
Operations: 5 patrols[2]
Victories:
  • 5 merchant ships sunk
    (10,709 GRT)
  • 4 merchant ships damaged
    (23,788 GRT)[2]

SM UB-68[Note 1] was a German Type UB III submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 20 May 1916. It was commissioned into the German Imperial Navy on 5 October 1917 as SM UB-68. The submarine conducted five patrols and sank five ships during the war. Under the command of Karl Dönitz, on 4 October 1918 UB-68 encountered technical problems and had to surface where she was sunk by gunfire at 33°56′N 16°20′E / 33.933°N 16.333°E / 33.933; 16.333. There was one dead and thirty-three survivors.[2] Other sources name the British warships involved in the sinking of UB-68 as HMS Snapdragon and HMS Cradosin, and claim four crew members died in the event.[4]

Summary of raiding history

[edit]
Date Name Nationality Tonnage[Note 2] Fate[5]
10 April 1918 Warwickshire  United Kingdom 8,012 Damaged
11 April 1918 Kingstonian  United Kingdom 6,564 Damaged
13 April 1918 Provence III  France 3,941 Damaged
26 April 1918 Angelina Di Paola  Italy 228 Sunk
1 June 1918 Angelina  Italy 1,260 Sunk
3 June 1918 Glaucus  United Kingdom 5,295 Sunk
12 June 1918 Monginevro  Italy 5,271 Damaged
24 June 1918 Saint Antoine  France 43 Sunk
4 October 1918 Oopack  United Kingdom 3,883 Sunk

Notes

[edit]

References

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Bibliography

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SM UB-68

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Design and construction

Type UB III characteristics

The Type UB III submarine represented the culmination of Germany's coastal U-boat design efforts in World War I, optimized for torpedo attacks and reconnaissance in confined waters such as the and , with enhanced range and endurance compared to earlier UB classes. These vessels featured a double-hulled configuration for improved survivability and streamlined hydrodynamics, allowing for greater submerged efficiency and operational flexibility in support of the unrestricted submarine campaign. Key technical specifications of the Type UB III class included a displacement of 516 tonnes when surfaced and 651 tonnes when submerged, providing a balanced compromise between compactness and payload capacity. The submarines measured 55.30 m in length overall, with a beam of 5.80 m and a draught of 3.68 m, enabling maneuverability in shallow coastal areas while maintaining stability. Propulsion was provided by twin diesel engines delivering 1,100 hp for surfaced operations and twin electric motors producing 788 hp for submerged travel, driving twin propellers to achieve maximum speeds of 13.6 knots surfaced and 8.0 knots submerged. This powerplant supported an operational range of 9,040 nautical miles at 6 knots on the surface and 55 nautical miles at 4 knots submerged, with a test depth of ~75 meters, allowing rapid evasion of surface threats. The complement consisted of 34 personnel, including 3 officers and 31 enlisted men, reflecting the class's emphasis on a compact but skilled crew for extended patrols. Armament comprised 5 × 50 cm tubes (4 bow, 1 ) with 10 es carried, supplemented by 1 × 8.8 cm for surface engagements.
SpecificationDetails
Displacement516 tonnes surfaced; 651 tonnes submerged
Dimensions: 55.30 m; Beam: 5.80 m; Draught: 3.68 m
Twin diesel engines (1,100 hp surfaced); Twin electric motors (788 hp submerged); Twin propellers
Speed13.6 knots surfaced; 8.0 knots submerged
Range9,040 nmi at 6 knots surfaced; 55 nmi at 4 knots submerged
Test depth~75 meters
Complement34 (3 officers, 31 men)
Armament5 × 50 cm tubes (4 bow, 1 ), 10 es; 1 × 8.8 cm

Building and commissioning

SM UB-68, the prefix "SM" denoting Seiner Majestät ("His Majesty's") in the nomenclature of the Kaiserliche Marine, was ordered on 20 May 1916 as part of the expanded UB III series to bolster Germany's coastal submarine force. Construction took place at the shipyard in , , under yard number 286. The submarine was launched on 4 July 1917 and subsequently fitted out for service. Following completion, UB-68 was commissioned into the Kaiserliche Marine on 5 October 1917. Her initial assignment involved training and shakedown operations in the relatively safe waters of the to test systems and train the crew, prior to her transfer to the Mediterranean theater for active duty with the Pola/Mittelmeer I Flotilla.

Service history

Operations under von Heimburg

SM UB-68 was placed under the command of Kapitänleutnant Heino von Heimburg upon her commissioning into the Kaiserliche Marine on 5 October 1917. Following initial fitting out in Germany, the submarine transited to the Mediterranean and joined the Mittelmeer I Flotilla on 8 January 1918, operating from the base at Pola (now Pula, Croatia) in the northern Adriatic. Under von Heimburg's leadership, UB-68 conducted her first three war patrols between April and June 1918, focusing primarily on the Adriatic Sea and extending into the eastern Mediterranean to interdict Allied merchant traffic. These operations formed part of a broader German intensification of the in the Mediterranean during , aimed at disrupting vital supply lines to and that sustained Allied forces on the Western Front. By early , German submarines from bases like Pola targeted shipping routes through choke points such as the , contributing to heightened pressure on Entente logistics amid . The Type UB III design of UB-68, with its compact size and twin-propeller configuration, proved well-suited for navigating the relatively confined waters of the Adriatic and , enabling sustained patrols despite the region's tactical constraints. Early successes underscored UB-68's effectiveness in this theater. In April 1918, during her initial patrols, she damaged the British passenger steamer Warwickshire (8,012 GRT), the British steamer Kingstonian (6,564 GRT), and the French steamer Provence III (3,941 GRT), and sank the Italian sailing vessel Angelina Di Paola (228 GRT). On 1 June 1918, she sank the Italian steamer Angelina (1,260 GRT) west of Cape Granitola, . Two days later, on 3 June, the submarine torpedoed and sank the British steamer Glaucus (5,295 GRT) 20 nautical miles west of Cape Granitola, . On 12 June 1918, UB-68 damaged the Italian steamer Monginevro (5,271 GRT) in the off . On 24 June 1918, she sank the French sailing vessel Saint Antoine (43 GRT). These actions exemplified von Heimburg's aggressive tactics against isolated merchant vessels, yielding significant tonnage in support of the flotilla's objectives. However, UB-68 encountered mounting challenges during these patrols, including strengthened Allied systems escorted by destroyers and submarine chasers, which reduced opportunities for successful attacks. Additionally, extensive minefields, such as the Otranto Barrage across the , complicated transit from Adriatic bases into open Mediterranean waters, forcing U-boats like UB-68 to navigate hazardous gaps under constant patrol threat. Despite these obstacles, von Heimburg's command period through 1 July 1918 marked UB-68's initial contributions to the Mediterranean campaign, with the accounting for multiple Allied shipping losses before transitioning leadership.

Transition to Dönitz command

Oberleutnant zur See assumed command of SM UB-68 on 2 July 1918, succeeding von Heimburg after the latter's tenure that had seen the submarine's earlier successes in the Mediterranean. , an experienced officer who had previously commanded the minelaying submarine UC-25 from February 1918, brought a focus on tactical innovation shaped by his frontline service; this period aboard UB-68 proved formative in his development as a submariner, influencing his later strategies during when he rose to and commander of the . Under Dönitz's leadership, UB-68 shifted operations toward more aggressive interceptions of Allied convoys in the central Mediterranean during its final patrol from September to October 1918, adapting to intensified Allied measures that had reduced earlier effectiveness. He emphasized surfaced night attacks to exploit visibility limitations and evade screens, a tactic that prefigured the coordinated wolfpack approaches he would refine in the next war by allowing submarines to close on targets undetected. This approach was evident in UB-68's last engagement, where Dönitz successfully sank the British steamer Oopack (3,883 GRT) during a night surface on a off on 4 October 1918, marking his sole confirmed success in command before technical malfunctions forced the boat to surface. The 34-man crew, consisting of three officers and 31 ratings typical of the UB III class, operated under Dönitz's disciplined leadership amid the submarine's deteriorating condition and the war's closing stages, maintaining operational readiness despite mounting Allied pressure. This transition marked UB-68's pivot to high-risk convoy hunting in the war's final months, reflecting broader German efforts to disrupt Mediterranean supply lines before the .

Combat record

Patrol engagements

SM UB-68 undertook five patrols in the Mediterranean theater from 8 January to 4 October 1918, accumulating roughly 150 days at sea across its operational career. The patrols focused on the , , central Mediterranean near , and waters off , targeting Allied convoys and shipping routes. The first successes occurred during the initial patrol in the Adriatic approaches in April 1918. Subsequent operations in May– extended into the Ionian and central Mediterranean. Command transferred to Oberleutnant zur See Karl Dönitz on 2 July 1918; under his leadership, UB-68 conducted its final patrol in September–October 1918, pursuing convoys east of Malta and culminating in the boat's loss due to mechanical failure on 4–5 October. Throughout these missions, UB-68 relied on standard tactics such as submerged torpedo launches to ambush targets and occasional surfaced gunfire against isolated vessels, adapting to the confined waters and heavy traffic of the Mediterranean. Patrols were frequently menaced by Allied anti-submarine warfare, including depth charge attacks from destroyers, underscoring the escalating effectiveness of convoy escorts and patrol sweeps in countering U-boat incursions.

Ships sunk and damaged

During its five patrols in 1918, SM UB-68 sank five merchant vessels totaling 10,709 gross register tons (GRT) and damaged four others totaling 23,788 GRT, contributing to the disruption of Allied supply lines in the Mediterranean theater. These figures represent confirmed successes based on postwar records from the German Imperial Navy and Allied shipping logs, with gross register tonnage (GRT) serving as the standard measure of a ship's internal volume in cubic feet, equivalent to 100 cubic feet per ton. The attacks primarily targeted steamers and sailing vessels carrying cargo essential to Allied logistics, though the submarine's overall impact was limited by its short operational lifespan and the intensifying Allied antisubmarine measures. The sunk ships included:
DateNameNationality/TypeGRTLocation
26 April 1918Angelina Di PaolaItalian sailing vessel228Mediterranean Sea north of Cape San Vito, Sicily (Adriatic approaches)
1 June 1918AngelinaItalian steamer1,260Ionian Sea
3 June 1918GlaucusBritish steamer5,295Mediterranean Sea west of Cape Granitola, Sicily (off Cape Matapan vicinity)
24 June 1918Saint AntoineFrench sailing vessel43Mediterranean Sea near Syracuse, Sicily
4 October 1918OopackBritish steamer3,883Adriatic Sea (central Mediterranean east of Malta)
The damaged ships were:
DateNameNationality/TypeGRTLocation
10 April 1918British passenger steamer/tanker8,012Western Mediterranean (convoy attack)
11 April 1918KingstonianBritish steamer6,564Off , western Mediterranean
13 April 1918Provence IIIFrench steamer3,941Western Mediterranean
12 June 1918MonginevroItalian steamer5,271Near ,
These operations occurred amid UB-68's patrols from bases in the Adriatic and western Mediterranean, where the boat exploited vulnerabilities to inflict measurable but not decisive losses on Allied merchant shipping.

Sinking and legacy

Circumstances of loss

On 4 October , during its fifth war patrol from Pola as part of the Pola/Mittelmeer Flotilla, SM UB-68 under the command of zur See conducted a night surface attack on an Allied in the central east of . The successfully torpedoed and sank the British steamer SS Oopack (3,883 gross register tons) around 01:00 hours, but as it repositioned for additional strikes between 02:30 and 03:30, two subsequent torpedoes malfunctioned, failing to launch properly. This triggered a catastrophic technical failure: an uncontrollable dive that pushed the boat beyond its designed maximum depth of 250 feet (76 meters) to approximately 330 feet (100 meters), risking structural collapse and forcing an emergency surfacing stern-first at position 33°56′N 16°20′E. Upon surfacing, UB-68 was immediately detected by the convoy escorts and subjected to heavy gunfire from the British Arabis-class sloop HMS Snapdragon and the armed trawler HMS Cradosin. Shells struck the , causing significant damage and rendering it unable to submerge or evade. With the vessel immobilized and under continuous fire, Dönitz ordered the crew to abandon ship; the engineer opened the sea cocks to scuttle the boat, which sank in about 8 seconds. Four crew members—Wilhelm Fackert, Willie Funke, Paul Jäschen, and Christ Thelen—were killed during the engagement, while 33 survivors, including Dönitz, were rescued from the water and taken prisoner by HMS Snapdragon. The sinking was confirmed by aligned Allied reports and postwar German naval records, attributing the loss to a surface action directly resulting from the submarine's mechanical defects amid the attack. Dönitz and his crew were interrogated by British intelligence, yielding insights into Austro-Hungarian U-boat operations. In later reflections, Dönitz credited the incident—particularly the vulnerability of single submarines to escorts—with shaping his strategies, including the development of wolfpack tactics to overwhelm defenses through coordinated group attacks and a focus on enhancing reliability.

Postwar significance

Karl Dönitz commanded SM UB-68 from July to October 1918, a period during which the submarine conducted patrols in the . This three-month tenure ended with the boat's sinking, an event that profoundly shaped Dönitz's views on . Captured by British forces after the sinking, Dönitz reflected on the vulnerabilities of the small, coastal-oriented UB III-class vessels like UB-68, which he believed were ill-suited for extended oceanic operations against superior enemy escorts. These experiences during his command influenced his postwar advocacy for developing larger, faster ocean-going U-boats capable of sustained patrols and evading detection, as well as the wolfpack tactics he later implemented to coordinate multiple submarines for mass attacks on convoys in . The wreck of SM UB-68 lies at coordinates 33°56′N 16°20′E in the central , at a depth exceeding 2,000 meters, rendering salvage operations impractical due to technical challenges and the lack of strategic value postwar. No recovery efforts have been documented, consistent with international agreements limiting naval salvage in following the , which dismantled much of the and focused Allied priorities on surface fleet reparations rather than submerged relics. UB-68 features prominently in Dönitz's memoirs, Ten Years and Twenty Days, where he describes his command as a formative episode that highlighted the limitations of in constrained theaters. As part of the intensified 1918 Mediterranean U-boat campaign, UB-68 contributed to sinking over 1 million tons of Allied shipping across the region that year, yet the overall effort failed to disrupt supply lines sufficiently to alter the war's outcome amid Allied protections and antisubmarine advances. In contrast to the high casualties of the German service—178 boats lost with approximately 5,000 men killed—UB-68's sinking resulted in four fatalities among its crew, underscoring the relatively lower risks in some late-war Mediterranean operations. Today, UB-68 is examined in naval histories as an exemplar of the evolutionary shift from short-range coastal to more versatile designs capable of oceanic deployment, informing studies on the tactical adaptations that bridged and II submarine doctrines.
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