The situation for the allies worsened in 1940, with the fall of France the U-boats gained access to the French Atlantic ports halving the distance to their refuelling stations, and eliminating any dangers of passing British weapons. 9
These advantages lead to the so-called happy time, from July to August, with over 200 merchant ships sunk10
By early 1941 the allied had developed the Destroyer escort, which was specifically designed to hunt submarines. 11 It was fitted with ship-based radar with a range of up to 25 miles, which was capable of detecting the smallest wake caused by the periscope head of a U-boat. 12The submerged submarines were detected by using Asdic, a sound detecting system, which enabled the allies to find U-boats in combats13 at a range of usually 300m. 14 The killing rate in comparison with the vintage escorts increased from 6 to 20 percent as the escorts were fitted with hedgehog a weapon designed specifically against U-boats. 15
Due to allied code breaking efforts, the allies were able to read Hydra, the code for all U-boats and ships in the northern sea and the Baltic, 16 from June to December 1941 within approximately 48 hours17 .In addition to this, the USA, who had been supplying Britian with ships previously, entered the Naval war.18 in December.
The entry of the USA immediately triggered a reaction in the Atlantic, “Admiral Dönitz immediately started an attack of full scale along the American east cost” 19 This attack, named Operation Drumbeat (Paukenschlag), started in January 20. ,since there were no convoys or escorts present on the American coast it was extremely successful 21.Leading to the second happy time with over 200 American ships sunk along the coast. 22.As a consequence USA introduced the convoy system in May23.
Due to German suspicions that there naval code had been broken, the U-boats were detached from Hydra and put on a new cipher, Triton, which linked them directly with the U-boat command. 24 “This cipher produced an almost total stoppage of intelligence.” 25 .In 1942, a total of 1000 merchant ships were sunk with the loss of only 85 U-boats. 26 Not until December 1942 the allies were able to break into the Triton cipher 27 Due to this breakthrough was the British were now confirmed with underlying suspicions of the convoy cipher being broken. 28 And in June 1943 the new codes were distributed to hundreds of users over the world. 29 Throughout the war the allied solved 50 percent of the naval enigma traffic. 30 In 1943 the U-boats effectiveness drastically decreased as it only sunk 310 merchant vessels at the cost of 254 U-boats. 31By 1944, the allies were sinking more U-boats then the Germans could construct. 32As a consequence, “on the 4th of May 1945 Dönitz called the U-boats to cease hostiles and return to bases, followed four days later by Germanys unconditional surrender” 33
1.Pitt, Barrie Slaget om atlanten p.21 translated
2.Flaherty, Thomas Krig till sjöss p.19 translated
3.Pitt p.63
4.Ibid p.23
5. Williamson, Gordon U-boats vs. Destroyer Escorts The Battle of the Atlantic p.5
6. Ibid.
7. Kahn, David Seizing the Enigma the race to break German U-boat codes, 1939-1943p.48
8. Ibid
9. Keegan, John Battle at Sea from Man-Of-War to Submarine p. 227
10.Williamson p.6
11. Ibid p.18
12. Ibid p.43
13. Ibid p.45
14. Ibid p.46
15. Keegan p. 239
16. Lewin, Ronald Ultra goes to war the secret story p. 207
17. Ibid p.209
18. Pitt 154
19. Ibid.
20. Ibid.
21. Ibid.
22. Williamson p.7
23. Pitt p. 154
24. Lewin 210
25. Ibid
26. Williamson p.76
27. Lewin p. 212
28. Ibid p. 213
29. Ibid.
30. Ratcliff, R.A. Delusions of intelligence Enigma, Ultra, and the end of Secure Ciphers p.3
31. Wiliamson p. 75
32. Ibid.
33. Central office of Information The Battle of the Atlantic p. 5
C. Evaluation of sources.
Seizing The Enigma the race to break the German U-boat codes, 1939-1943 published in 1996 by David Kahn provides a detailed account for Intelligence throughout the battle of the Atlantic. Its purpose is to analyse and describe the successes, failures and values of Allied code breaking. David Kahn holds a D. Phil. in modern history from the University of Oxford and is currently an editor at Newsday. 1 Given that he is a journalist he lives from his Writings and is not funded by any organization, this is reflected throughout the book since Kahn attempts to add tension to the history of code breaking by accounting for it in a narrative form. This causes a certain amount of bias within the book when referring to the importance of Ultra. The values of the book are the in-depth look at operation Ultra and the history of seizing the German intelligence with a great expertise. Furthermore, Kahn gives an analysis of the importance of individual and character in converting Intelligence into effective operations.
While Seizing the Enigma is focused only on intelligence and its effects in the Atlantic, John Keegan’s Battle at Sea from Man-Of-War to Submarine published in 2004 is purposed to provide a broad, comprehensive overview of naval ware faring in modern times. John Keegan is Defense editor of the Daily Telegraph and has lectured at many Universities throughout the years. 2 Considering his profession and his British Origins one can say that the Keegan may bias his discussion when accounting for the British role in the Battle. The book is also limited because of its brief overview it does not give all details to understand the complexity of the Battle of the Atlantic thoroughly. It values are that it is easily understood, and provides an insight into naval operations, strategies, and technology. Considering the broad perspective Keegan has, offers a slightly more objective when referring to intelligence throughout the war than in Seizing the enigma.
- Kahn p.1
- Keegan p.1
D. Analysis
Although, the Battle of the Atlantic was fought at sea it was dictated by actions taken on land. One of these was the breaking of the German Enigma code as its extent to which it contributed to allied victory in The Battle of the Atlantic is considered.
Ultra could be utilized to a great extent in offensive operations. The versatileness of the U-boat made it difficult to destroy for the allies. The intelligence acquired through the cracking of the Enigma code gave the allies insight into position and plans of the U-boats, and enabled them to send their troops to their most vulnerable points. 1 Ultra gave information that was highly valuable to the Allies such as where refuelling was to take place, and where the U-boats where currently patrolling. 2 However, the inconsistency with which Ultra was broken and the limited amount of messages read makes the actual operational value hard to assess. Even when Ultra was broken operational success was often dependent how the commanders used the information. 3According to Lewin, airborne radar, reinforcement of escort carriers, the stiffening of the costal command and the mounting efficiency of warships was mainly responsible for the increase in offensive successes in 1943. 4 Nevertheless, it is undisputed that Ultra aided the allies in offensive missions to some degree; coordinating the aeroplanes and escorts by having complete insight into the U-boats strategies.
Ultra aided the allies to protect merchant shipping. Intelligence acquired by Ultra aloud the allied to foresee attacks by wolf packs and circle any lurking U-boats. 5 In late 1941, the U-boats sighted one out of every ten convoys, in 1942 this figure increased to one out of three convoys. 6 However, it is not certain how much of this was attributable to Ultra. According to Keegan, the German success in 1942, were because of the increased number of U-boats available to Dönitz. 7 In another interpretation, the increased success was because of USA lack of experience in naval ware faring. 8 Furthermore, the increasing strength of the Convoy Escorts and the effective anti submarine weaponry can be held responsible for the dramatic decline in convoys lost in 1943. 9 However, the detection of the B-Dienst success of breaking into allied convoy codes in 1943 undoubtedly made warfare for the U-boats more complex. 10 Although, it is difficult to determine how much Information was usable for the defence of the Convoys it can certainly be said that Ultra aided the protection to a large extent.
Many other factors were important for the outcome of the Battle of the Atlantic. The employment of the U-boats was a more desperate mean of defeating a Superior allied fleet. 11 Nevertheless, it can be said that the allied were largely unprepared for the threat posed by the U-boats. 12 Although, Williamson and Keegan are in disagreement over the role of the U-boat one can certainly say that because plan Z was not finished the Germans were unprepared for a war with the British fleet .13And even when Germany solely focused on U-boat production the Entry of the USA enabled the allied to outstrip the German industrial capacity. 14 “The entry of the USA into the war brought not just significant numbers of escort warships (…), but perhaps even more significantly, the industrial capacity to mass manufacture cargo ships with the arrival of Henry Kaisers famed liberty ships.” 15 However, it can be argued that American crews were largely inexperienced in naval warfare. 16
Ultra contributed to allied victory by positioning the U-boats and coordinating attacks, aloud the allies to increase means of convoy protection. Considering the superiority of Fleet and Industrial capacity of the allied, Ultra can be held partially responsible for allied victory at sea.
- Ratcliff p.4
- 2.Kahn p.274
- Lewin p.222
- Ibid p.218
- Kahn p.216
- Ibid.
- Keegan p. 222
- Williamson p.13
- Ibid p.47
- Keegan p. 243
- Williamson p.4
- Keegan p. 216
- Pitt p.21
- Williamson p.77
- Ibid.
- Ibid. p.24
E. Conclusion
It is impossible to say that Ultra was solely responsible for successful allied operations at Sea. The Destroyer Escort and Aeroplanes with their effective Anti-Submarine weaponry also played a major role in hunting down U-boats and defending Convoys. 1 Furthermore, the actual operational of the Intelligence is hard to access since it was higly dependent on a number of factors. 2 Nevertheless, it can be said that Ultra was mainly responsible for successful operations at sea. However, the Germans were unprepared for a war with Britain and with the entrance of America their industrial capacity was outstripped. Therefore, it can be said that that Ultra contributed to Allied victory but only to a limited extent. Although, the offensive implications of Ultra were highly valuable to the allies, and the cracking of Enigma certainly aided the defence of the convoys, the vast industrial capacity of America and the superiority of the allied fleet also were significant for the allied success.
It can not be said that Ultra won the battle of the Atlantic, although it was highly relevant to operations at sea, there were many other factors leading to the victory in the Atlantic.
- Williamson p.77
- Ratcliff p.3
- List of sources
Flaherty, Thomas H. Krig till sjöss Amsterdam: Time life books, 1992
Central office of Information The Battle of the Atlantic London: H.M stationary office, 1946
Pitt, Barrie Slaget om Atlanten Amsterdam: Time Life books, 1981
Kahn, David Seizing the Enigma the race to break German U-boat codes, 1939-1943 London: Arrow books, 1996.
Keegan, John Battle at Sea from Man-Of-War to Submarine London: Pimlico military classics, 2004
Lewin, Ronald Ultra goes to war the secret story London: Hutchinson & Co. , 1978
Ratcliff, R.A. Delusions of intelligence Enigma, Ultra, and the end of Secure Ciphers Cambridge: Cambridge University press, 2006
Showell, J.P Mallmann Enigma U-boats Surrey: Ian Allen publishing, 2000
Williamson, Gordon U-boats vs. Destroyer Escorts The Battle of the Atlantic Oxford: Osprey publishing, 2007.
