SM U-66
History | |
---|---|
German Empire | |
Name | U-66 |
Ordered | 2 February 1913 |
Builder | |
Yard number | 203[1] |
Laid down | 1 November 1913, as U-7 (Austria-Hungary)[1] |
Launched | 22 April 1915[1] |
Commissioned | 23 July 1915[1] |
Fate | Missing since 3 September 1917, possibly in the Dogger Bank area to a mine. 40 dead (all hands lost)[1] |
General characteristics [3] | |
Type | German Type U 66 submarine |
Displacement |
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Length |
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Beam |
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Height | 7.95 m (26 ft 1 in) |
Draft | 3.79 m (12 ft 5 in) |
Propulsion |
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Speed |
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Range |
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Test depth | 50 m (160 ft) |
Complement | 4 officers, 32 enlisted men |
Armament |
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Service record | |
Part of: |
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Commanders: | |
Operations: | 7 patrols |
Victories: | |
SM U-66 was the
Under German control, the class became known as the U-66 type and the boats were renumbered; U-7 became U-66, and all were redesigned and reconstructed to German specifications. U-66 was launched in April 1915 and commissioned in July. As completed, she displaced 791 tonnes (779 long tons) when surfaced and 933 tonnes (918 long tons) submerged. The boat was 69.50 metres (228 ft) long and was armed with five torpedo tubes and a deck gun.
As a part of the Baltic and IV Flotillas, U-66 sank 25 ships with a combined gross register tonnage of 73,847 in six war patrols. The U-boat also torpedoed and damaged the British cruiser Falmouth in August 1916. U-66 left Emden on her seventh patrol on 2 September 1917 for operations in the North Channel. The following day the U-boat reported her position in the North Sea but neither she nor any of her 40-man crew were ever heard from again. A postwar German study offered no explanation for U-66's loss, although British records suggest that she may have struck a mine in the Dogger Bank area.
Design and construction
After the Austro-Hungarian Navy had competitively evaluated three foreign submarine designs, it selected the Germaniawerft 506d design, also known as the Type UD, for its new U-7 class of five submarines.[6] The Navy ordered five boats on 1 February 1913.[7]
The U-7 class was seen by the Austro-Hungarian Navy as an improved version of its
U-7 and
U-7 was renumbered by the Germans as U-66 when her class was redesignated as the Type U-66. The Imperial German Navy had the submarines redesigned and reconstructed to German standards, increasing the surface and submerged displacements by 96 and 48 tonnes (94 and 47 long tons), respectively. The torpedo load was increased by a third, from 9 to 12, and the deck gun size was upgraded from the 6.6-centimeter (2.6 in) size originally specified to 8.8 cm (3.5 in) SK L/30.[2]
Early career
U-66 was launched on 22 April 1915.[2] On 23 July, SM U-66 was commissioned into the Imperial German Navy under the command of Kapitänleutnant (Kptlt.) Thorwald von Bothmer,[1] a 31-year-old, thirteen-year veteran of the Imperial German Navy.[4] U-66 was assigned to the Baltic Flotilla (German: U-boote der Ostseestreitkräfte V. Unterseeboots-Halbflottille) on 17 October.[9]
In late September, the British submarine flotilla in the Baltic began a submarine offensive against German ships, intending to deny free passage of cargo, especially iron ore, from neutral Sweden to Germany.[10] In A Naval History of World War I, author Paul G. Halpern reports on part of the German response, which was an experiment involving U-66. The U-boat was towed behind an "innocent-looking vessel" and connected to the host ship by a telephone line in addition to the towline. U-66 was able to cast off at a moment's notice to attack an enemy submarine. Halpern does not report on any encounters by U-66, nor does he provide any insight into the overall effectiveness of the plan.[11] U-66 was not credited with the sinking of any vessels of any kind during this time.[12] On 15 January 1916, she was transferred from the Baltic Flotilla into the IV Flotilla (German: IV. Unterseeboots-Halbflottille), where she joined her sister boats U-67 and U-68.[9][Note 4]
Second German offensive
Germany began its
U-66 continued her attacks on merchant shipping on 9 April with the sinking of three ships, the British steamers Eastern City and Glenalmond and the Norwegian ship Sjolyst.
U-66 finished out her busy month the next day by sinking one British and one Italian ship. U-66 sank the British steamer Margam Abbey 55 nautical miles (102 km; 63 mi) southwest of the Lizard while the ship was en route from Bordeaux to Barry Roads in ballast. Margam Abbey, at 4,471 tons, was the largest ship sunk by U-66 to that time.[12][25] The Italian freighter Unione was sailing with a load of coal from Clyde for Genoa when U-66 torpedoed her off Land's End. The sinking of Unione, with a tonnage of 2,367, raised U-66's tally for the month of April to nine ships with a combined tonnage of 22,848,[12] all sunk in a six-day span. Near the end of April 1916, Admiral Reinhard Scheer, the new commander-in-chief of the High Seas Fleet (under which U-66's IV Flotilla operated), called off the merchant shipping offensive and ordered all boats at sea to return, and all boats in port to remain there.[26]
Grand Fleet ambushes
In mid-May 1916, Scheer completed plans to draw out part of the British
A delayed departure of the German fleet for its sortie (which had been redirected to the Skagerrak) and the failure of five U-boats, including U-66, to receive the coded message warning of the British advance caused Scheer's anticipated ambush to be a "complete and disappointing failure".[29] Although she had not received the advance warning of the coded message, U-66 was one of the two ambush U-boats that actually saw parts of the British fleet.[29] At 09:00 on 31 May, U-66 sent out a wireless report of eight battleships, light cruisers, and destroyers on a northerly course 60 nautical miles (110 km; 69 mi) east of Kinnaird Head.[30][Note 5] U-66 was unable to make any attacks on the ships she reported due to the presence of screening vessels.[30] 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.[31]
The next mention of U-66 in sources is on 11 August, when she sank Inverdruie, a 613-ton three-masted Norwegian bark. Inverdruie was carrying a load of pit props from Sandefjord to Hartlepool when she was sunk some 160 nautical miles (300 km; 180 mi) east of Aberdeen.[32][33]
Later in August, the Germans set up another ambush for the British fleet, when they drew up 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. U-66 was one of 24 U-boats that formed five lines (German: Standlinie) in the expected paths of any Grand Fleet sorties. Standlinie II, consisting of U-63, U-49, U-45, U-66, and U-64, formed a 35-nautical-mile (65 km; 40 mi) front 12 nautical miles (22 km; 14 mi) off Flamborough Head. The other four Standlinie formed similar lines to the north and south; all were to be in place by 08:00 on 19 August. 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.[34]
At 04:45 on 19 August, U-66 fired a spread of two torpedoes at the British light cruiser
Records on U-66 next appear in late 1916, when she is reported as one of the U-boat escorts assisting the German
Unrestricted submarine warfare
From the early stages of the war the Royal Navy had blockaded Germany, preventing neutral shipping from reaching German ports. By the time of the so-called "turnip winter" of 1916–17, the blockade had severely limited imports of food and fuel into Germany.
U-66's first victim under the new rules was encountered on 1 March. The Norwegian steamer Gurre, reported as 1,733 tons, was crossing the North Sea while steaming from
In late March, U-66 sank another two vessels. The 3,597-ton cargo ship Stuart Prince was headed from Manchester and
During April 1917, German U-boats sank 860,334 tons of Allied and neutral shipping, a monthly total unsurpassed in either of the two world wars.[53] U-66's sole contribution to this figure came when she torpedoed the tanker Powhatan 25 nautical miles (46 km; 29 mi) from North Rona in the Outer Hebrides.[21] The 6,117-ton ship, which was carrying fuel oil from Sabine, Texas to Kirkwall, bested Margam Abbey as U-66's largest ship sunk when she went down with 36 of her crew.[12][21] As was done with the master of Neath, Powhatan's master was taken prisoner aboard U-66.[21]
Although the monthly total of tonnage sunk by all U-boats had peaked in April, the losses were over 600,000 tons in each of May and June. U-66 did not contribute to the May tally but, with her most successful month since April 1916, added to the June figures.[12] On 5 June, U-66 torpedoed the 3,472-ton Italian steamer Amor which was on her way to Liverpool from Galveston; Amor sank approximately 200 nautical miles (370 km; 230 mi) from Fastnet Rock.[54][55] The same day, Manchester Miller, a 4,234-ton steamer sailing from Philadelphia for Manchester with a load of cotton, was sunk about 10 nautical miles (19 km; 12 mi) away from Amor when she was hit by a torpedo from U-66. Eight crewmen died in the attack; the survivors, who included three Americans, were landed on 9 June.[56][57]
Two days after the attacks on Amor and Manchester Miller, U-66 attacked two more British steamers. The 4,329-ton Ikalis, carrying wheat from New York to Manchester, was torpedoed and sunk 170 nautical miles (310 km; 200 mi) from Fastnet Rock.[58] The cargo ship Cranmore, of 3,157 tons, was headed to Manchester from Baltimore with a general cargo when torpedoed some 150 nautical miles (280 km; 170 mi) northwest of Fastnet. Though the ship was damaged, Cranmore's crew was able to beach her; the ship was later refloated and re-entered service.[59]
U-66 sank her largest ship, the 6,583-ton British steamer Bay State on 10 June.[12] The Warren Line cargo steamer had departed from Boston (the capital of Massachusetts nicknamed, coincidentally, the "Bay State") with a $2,000,000 war cargo destined for Liverpool. U-66 intercepted the ship 250 nautical miles (460 km; 290 mi) northwest of Fastnet and sank her, but there were no casualties among her crew of 45.[22][60] Four days later, U-66 encountered the Norwegian bark Perfect, laden with grain, headed from Bahía Blanca for Copenhagen.[61] Perfect, which had been built in 1877, was dispatched by U-66's deck gun at position 60°58′N 2°18′E / 60.967°N 2.300°E, east of Shetland.[61][62]
On 17 June, Kptlt. von Bothmer was replaced by Kptlt. Gerhard Muhle as commander of the U-boat.
U-66 scored another success when she torpedoed and sank the outbound British steamer African Prince on 21 July 60 nautical miles (110 km; 69 mi) north-northwest of Tory Island. The freighter—a Prince Line line-mate of Stuart Prince, sunk by U-66 in March—was carrying china clay from Liverpool to Newport News.[49] The same day, U-66 also sank the 1,322-ton British sailing ship Harold about 5 nautical miles (9.3 km; 5.8 mi) from where African Prince went down.[64] These two ships were the last sinkings credited to U-66.[12] During six successful patrols,[1] U-66 had sunk 25 ships and seized a 26th as a prize, for a combined total tonnage of 74,852.[12]
U-66 began her seventh and what was to be her final patrol on the morning of 2 September when she departed from Emden destined for operations in the North Channel. Shortly after noon on 3 September, U-66 reported a position in the North Sea that placed her beyond known British minefields, in what was her last known contact. A postwar German study offered no explanation for U-66's loss. British records suggest that U-66 may have either struck a mine in an older minefield in the Dogger Bank area, or that a combination of destroyers, submarines, and anti-submarine net tenders sank U-66 sometime between 1 and 11 October. Author Dwight Messimer discounts this latter theory as not being supported by operational details.[65]
Summary of raiding history
Date | Name | Nationality | [Note 6] Tonnage | Fate |
---|---|---|---|---|
5 April 1916 | Zent | United Kingdom | 3,890 | Sunk |
6 April 1916 | Binicaise | France | 151 | Sunk |
7 April 1916 | Sainte Marie | France | 397 | Sunk |
7 April 1916 | Rijndijk | Netherlands | 3,557 | Damaged |
8 April 1916 | Santanderino | Spain | 3,346 | Sunk |
9 April 1916 | Eastern City | United Kingdom | 4,341 | Sunk |
9 April 1916 | Glenalmond | United Kingdom | 2,888 | Sunk |
9 April 1916 | Sjolyst | Norway | 997 | Sunk |
10 April 1916 | Margam Abbey | United Kingdom | 4,471 | Sunk |
10 April 1916 | Unione | Kingdom of Italy | 2,367 | Sunk |
11 August 1916 | Inverdruie | Norway | 613 | Sunk |
19 August 1916 | HMS Falmouth | Royal Navy[34] | 5,250 | Damaged |
11 December 1916 | Bjor | Norway | 1,090 | Sunk |
11 December 1916 | Palander | Sweden | 311 | Sunk |
1 March 1917 | Gurre | Norway | 1,733 | Sunk |
1 March 1917 | Livingstone | Norway | 1,005 | Captured as prize |
22 March 1917 | Stuart Prince | United Kingdom | 3,597 | Sunk |
27 March 1917 | Neath | United Kingdom | 5,548 | Sunk |
6 April 1917 | Powhatan | United Kingdom | 6,117 | Sunk |
5 June 1917 | Amor | Kingdom of Italy | 3,472 | Sunk |
5 June 1917 | Manchester Miller | United Kingdom | 4,234 | Sunk |
7 June 1917 | Cranmore | United Kingdom | 3,157 | Damaged |
7 June 1917 | Ikalis | United Kingdom | 4,329 | Sunk |
10 June 1917 | Bay State | United Kingdom | 6,583 | Sunk |
10 June 1917 | Highbury | United Kingdom | 4,831 | Sunk |
14 June 1917 | Perfect | Norway | 1,088 | Sunk |
9 July 1917 | Iparraguirre | Spain | 1,161 | Sunk |
21 July 1917 | African Prince | United Kingdom | 4,916 | Sunk |
21 July 1917 | Harold | United Kingdom | 1,376 | Sunk |
[Note 7]Sunk: Damaged: Total: |
74,852 11,964 86,816 |
Notes
- ^ The U-3-class submarines, however, were less than half the displacement and nearly 90 feet (27 m) shorter than the U-7 design. See: Gardiner, pp. 342–43.
- in 1909. See: Sieche, p. 19.
- ^ In April 1915, just five months later, the German U-21 successfully entered the Mediterranean through the Strait of Gibraltar, proving that delivery could have been possible after all. See: Gardiner, p. 343.
- ^ Both of U-66's remaining sister boats, U-69 and U-70, were attached to the IV Flotilla by early March, and for just under three weeks (until U-68 was sunk), all five of the Type U 66 boats were in the same unit. See; Tarrant, p. 30 (for sinking of U-68), and p. 34 (for Flotilla membership).
- ^ The other U-boat that reported activity, SM U-32, stationed 155 nautical miles (287 km; 178 mi) off the Firth of Forth, had reported seeing two battleships, two cruisers and several destroyers headed in a southeasterly direction two hours earlier.
- gross register tons. Military vessels are listed by tons displacement.
- ^ Tonnage of ships captured as prizes is included in tonnage sunk.
References
- ^ a b c d e f g h i Helgason, Guðmundur. "WWI U-boats: U 66". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 9 December 2008.
- ^ a b c d Gardiner, p. 177.
- ^ a b c d e f Gröner 1991, p. 10.
- ^ a b c Helgason, Guðmundur. "WWI U-boat commanders: Thorwald von Bothmer (Royal House Order of Hohenzollern)". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 12 January 2015.
- ^ a b Helgason, Guðmundur. "WWI U-boat commanders: Gerhard Muhle". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 12 January 2015.
- ^ Gardiner, p. 340.
- ^ Gardiner, p. 343.
- ^ a b Helgason, Guðmundur. "WWI U-boats: U 66", "U 67", "U 68", "U 69", "U 70". U-Boat War in World War I. Uboat.net. Retrieved 9 December 2008.
- ^ a b Tarrant, p. 34.
- ^ Halpern, p. 202.
- ^ Halpern, p. 204.
- ^ a b c d e f g h i j Helgason, Guðmundur. "Ships hit by U 66". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 9 December 2008.
- ^ Tarrant, pp. 27–28.
- ^ Tennent, p. 74.
- ^ "48 lost with liner". The Washington Post. 7 April 1916. p. 1.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Binicaise". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Details, location: Helgason, Guðmundur. "Ships hit during WWI: Sainte Marie". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008. Type of ship: "Nine killed on ship sunk by U-boat; four more vessels destroyed; three British". The New York Times. 9 April 1916. p. 1.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Santanderino". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ a b "Spanish liner warned". The Washington Post. 12 April 1916. p. 2.
- Chicago Daily Tribune. 11 April 1916. p. 2.
- ^ a b c d Tennent, p. 210.
- ^ a b Tennent, p. 100.
- ^ a b "U-boats sink six more British ships, also a Spanish and a Norse steamer". The New York Times. 11 April 1916. p. 1.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Sjolyst". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Tennent, p. 237.
- ^ Tarrant, p. 30.
- ^ a b c Gibson and Prendergast, p. 97.
- ^ a b Tarrant, p. 31.
- ^ a b Tarrant, p. 32.
- ^ a b Gibson and Prendergast, p. 99.
- ^ Tarrant, pp. 32–33.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Inverdruie". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Google (17 December 2008). "SM U-66" (Map). Google Maps. Google. Retrieved 17 December 2008.
- ^ a b c Tarrant, p. 33.
- ^ Hoyt, p. 20.
- ^ Halpern, pp. 372–73.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Bjor". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Norge". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008. The ship had been built in 1884 as Norge but was renamed Bjor in 1915.
- ^ "Seven more ships sunk". Chicago Daily Tribune. 15 December 1916. p. 4.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Palander". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Tarrant, pp. 44–45.
- ^ Tarrant, p. 45.
- ^ Tarrant, pp. 45–46.
- ^ Tarrant, p. 46.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Gurre". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Crimea". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008. The 1889 Crimea had been renamed several times, with her final name of Gurre attached earlier in 1917.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Livingstone". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Livingstone". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008.
- ^ a b Tennent, p. 99.
- ^ a b c Helgason, Guðmundur. "Ships hit during WWI: Neath". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "R. C. Rickmers". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008.
- ^ a b "Consul Frost reports loss of bark Neath". The Christian Science Monitor. 29 March 1917. p. 1.
- ^ Tarrant, p. 47.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Amor". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Caprera". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008. Caprera had been renamed Amor in 1911.
- ^ "Three Americans saved". The New York Times. 10 June 1917. p. 6.
- ^ Tennent, p. 163.
- ^ Tennent, p. 233.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Cranmore". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Twelve sinkings reported". The Washington Post. 21 June 1917. p. 1.
- ^ a b Helgason, Guðmundur. "Ships hit during WWI: Perfect". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ "Seiriol Wyn". Miramar Ship Index. R.B.Haworth. Retrieved 17 December 2008. Seiriol Wyn had been renamed Perfect in 1898.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Iparraguirre". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Helgason, Guðmundur. "Ships hit during WWI: Harold". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 17 December 2008.
- ^ Messimer, p. 85.
Bibliography
- Beesly, Patrick (1982). Room 40: British Naval Intelligence 1914–1918. London: H Hamilton. ISBN 978-0-241-10864-2.
- Gardiner, Robert; Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. Annapolis, Maryland: OCLC 12119866.
- Gröner, Erich; Jung, Dieter; Maass, Martin (1991). German Warships 1815–1945, U-boats and Mine Warfare Vessels. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
- Halpern, Paul G. (1994). A Naval History of World War I. Annapolis, Maryland: Naval Institute Press. OCLC 28411665.
- Hoyt, Edwin Palmer (1974). Raider Wolf: The Voyage of Captain Nerger, 1916–1918 (1st American ed.). New York: P.S. Eriksson. OCLC 1128815.
- Koerver, Hans Joachim (2008). Room 40: German Naval Warfare 1914–1918. Vol I., The Fleet in Action. Steinbach: LIS Reinisch. ISBN 978-3-902433-76-3.
- Koerver, Hans Joachim (2009). Room 40: German Naval Warfare 1914–1918. Vol II., The Fleet in Being. Steinbach: LIS Reinisch. ISBN 978-3-902433-77-0.
- Messimer, Dwight R. (2002). Verschollen: World War I U-boat losses. Annapolis, Maryland: Naval Institute Press. OCLC 231973419.
- Roessler, Eberhard (1997). Die Unterseeboote der Kaiserlichen Marine. Bonn: Bernard & Graefe. ISBN 978-3-7637-5963-7.
- Schroeder, Joachim (2002). Die U-Boote des Kaisers. Bonn: Bernard & Graefe. ISBN 978-3-7637-6235-4.
- Sieche, Erwin F. (1980). "Austro-Hungarian Submarines". Warship, Volume 2. Annapolis, Maryland: Naval Institute Press. OCLC 233144055.
- Spindler, Arno (1966) [1932]. Der Handelskrieg mit U-Booten. 5 Vols. Frankfurt: Mittler & Sohn. (Vols. 4+5, dealing with 1917+18, are very hard to find: Guildhall Library, London, has them all, also Vol. 1–3 in an English translation: The submarine war against commerce)
- Tarrant, V. E. (1989). The U-Boat Offensive: 1914–1945. Annapolis, Maryland: Naval Institute Press. OCLC 20338385.
- Tennent, A. J. (2006) [1990]. British Merchant Ships Sunk by U boats in the 1914–1918 War. ISBN 1-904381-36-7.
External links
- Photos of cruises of German submarine U-54 in 1916–1918.
- A 44 min. German film from 1917 about a cruise of the German submarine U-35.
- Helgason, Guðmundur. "WWI U-boats: U 66". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net.
- Room 40: original documents, photos and maps about World War I German submarine warfare and British Room 40 Intelligence from The National Archives, Kew, Richmond, UK.