Seizing the Enigma: The Race to Break the German U-Boat Codes, 1933-1945

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Seizing the Enigma: The Race to Break the German U-Boat Codes, 1933-1945 Page 37

by Kahn, David


  131

  rotors VI and VII: Hinsley, 3:2:957. He states at 1:336 that three rotors were captured from the U-33, but that one of those captured may already have been known.

  132

  Herivel tip: Herivel interview; Welchman, Hut Six Story, 98–99; Welchman, “From Polish Bomba,” 99, 107.

  133

  “Royal Flags Wave Kings Above”: Monroe interview.

  133

  May 22, 1940: Hinsley, 1:109, 144.

  134

  83 percent: Rejewski, “Remarks on Appendix 1,” 81.

  134

  hundred keys: Hinsley, 1:493; Bertrand, 79.

  134

  “Concerning directive”: Bertrand, 285.

  136

  encouraged Naval Section: Hinsley interview.

  138

  Radio Cipher H, Dockyard: Morris, 115–16; M.Dv. Nr. 103.

  147

  “the recent recrudescence”: Winston S. Churchill, Blood, Sweat, and Tears (New York: Putnam’s, 1941), 411.

  147

  atmosphere not disheartened but industrious: Wylie and Hinsley interviews.

  10. In the Locked Drawer of the Krebs

  Information on the Tribal class destroyers and the Somali is from Brice, 7,15–18, 228–34; Peter Hodges, 6–7, 10, 53; Wellings, 47, 53, 57, 58, 60. All details of the raid on Norway are from DEFE 2/142, which includes some information deleted from Tovey; MA:M8i5/472i9:4.3. [19411:1435; interviews with Warmington, Stuart-Menteth, Low, and Harper-Gow; and Roskill, War at Sea, 1:341–342. On Warmington: Warmington interview; Who’s Who, 1990; Burke’s Peerage and Baronetage 103 (1963), 2505.

  11. Kisses

  Information about Wylie, Good, Brett-Smith, and Lever and on life at Bletchley is from Good, 7; and from interviews with Good, Hilary Hinsley, Barbara Eachus, and Mavis Batey. Details about banburismus, other Hut 8 cryptanalysis, and cribs are from Andrew Hodges, 197; Morris, 112–15; and interviews with Hinsley, Good, and Monroe. Direction-finding details are from Kemp interview. Information on Thring, Winn, and the Submarine Tracking Room is from MacLachlan, 102, 107–9; Beesly, Very Special Intelligence, 55–58, 158, 165–66, and passim.

  168

  Hut 4 handled non-Enigma: Hinsley interview.

  169

  “Gardening,” “special planting,” “Squares BF2927”: AIR 4/797:26A, 28A, and DEFE 3:27:ZTG/9880.

  173

  “who go out”: Winston S. Churchill, The Unrelenting Struggle: War Speeches (Boston: Little, Brown, 1942), 98.

  12. A Trawler Surprised

  Information on German weather ships is primarily from PG 36742 and, on their sailings, from PG 34814-34837. Details of the planning of the attack on the München are from Hinsley interview. Details of the attack are from ADM 199/447; ADM 53/114202; and interviews with Warmington, Low, Wiggeshof, and Rebelein. Bremerhaven, where the München was worked on, was then called Wesermünde.

  176

  “augmented weather report”: MA: M/19/36742:4.9.40.

  176

  U-Boat Command objected: Godt letter; Hessler, 145; Dönitz, 148.

  176

  October 24, Adolf Vinnen: PG 47109.

  177

  München: Lloyd’s Register of Shipping, No. 11470.

  177

  Wetterkurzschlüssel: M.Dv.Nr. 443.

  182

  three-page report: Hinsley, 1:565–69 (original is three pages long).

  183

  Holland: Ludovic Kennedy, Pursuit: The Chase and Sinking of the Bismarck (New York: Viking, 1974), 62; Ernie Bradford, The Mighty Hood (London: Hodder & Stoughton, 1959), 173.

  185

  “Werde gejagt”: PG 34833:7.5.41; DEFE 3:ZTP384.

  187

  “One of our patrols”: Times (May 10, 1941), p. 4, col. 6; PG 34832:10.5.41.

  187

  Hitler and Raeder discussed: Germany, Oberkommando der Kriegsmarine, Lagevorträge, 229, 231–38.

  13. The Staff School Memory

  The references are the same as those for Chapter 1.

  14. “All This Rubbish?”

  I am grateful to Captain Hugh Wilson and Chief Gunner’s Mate Thomas Kelly for reading a draft of this chapter and making extremely valuable comments and corrections.

  Details of the capture of the Lauenburg, unless otherwise specified, are from ADM 199/430; ADM 53/14797; Kelly, diary; and interviews with Wilson, Kelly, Kennedy, Braun, and Klarman. Information on Gewald is from Buhr, Gratz interviews and Mohr, passim. On Bacon, from Forster, Hinsley interviews. On Skipwith, from Wilson, Kelly interviews.

  199

  cryptanalysts would face delays: Hinsley interview.

  199

  Lauenburg: Lloyd’s Register of Shipping, No. 103 01.

  205

  “You don’t know”: Brice, 251.

  212

  Hinsley pleased: Hinsley interview.

  15. The Great Man Himself

  Churchill’s passion for solved intercepts is detailed in “Churchill Pleads for the Intercepts,” ed. David Kahn, Cryptologia 6 (January 1982), 47–49; Hinsley, 1:295; Gilbert, Finest Hour, 611–13, 814, 848–49. Aspects of his visit to Bletchley are from Finest Hour, 1185; Malcolm Kennedy, 439; Andrew Hodges, 205; Brown, 398; and interviews with Good, Milner-Barry, John and Mavis Batey, and Herivel.

  The cryptanalysts’ problems, their letter, and Denniston’s removal come from Hinsley, 2:25–28, 655–57, 272–74, 279, 286, 289–90; Milner-Barry, “Action This Day,” 272–76; R. A. Denniston, 116–17, 122–24; Filby, 275–76; Malcolm Kennedy, 440; Brown, 401–2; Milner-Barry, Monroe interviews. Travis is described in Who Was Who, 1950–1959; Malcolm Kennedy, 442; Welchman, Hut Six Story, 274; Brown, 397; Andrew Hodges, 177–78, 204; interviews with Milner-Barry, Twinn, and Davidson.

  The story of convoy HX 155 was assembled from U.S. Navy, Navy Historical Branch, Operational Archives, Tenth Fleet Files, Convoy and Routing Section, Folder for HX 155; that archive’s World War II Action Report, Commander Destroyer Division 62 (Commander Task Unit 4.1.7), Escort of Convoys HX 155 and ON 31; RG 24, Logbooks of U.S. S. Stur devant and U.S. S. Bainbridge; BdU, KTB, 1.–30.Oktober 1941; SRMN-033, 4–30 October 1941; Hinsley, 2:174; Rohwer, “‘Special Intelligence,’” 719; Rohwer, “Ultra and the Battle of the Atlantic,” 422.

  213

  solution times: The solution time was calculated for each intercept in DEFE from May to August 1941 and averaged for each month.

  213

  reasons for July–August tonnage loss decline: Macintyre, 87, 88, 91.

  214

  eight bombes: Hinsley, 1:338; Welchman, Hut Six Story, 139.

  214

  Pound: Malcolm Kennedy, 439.

  215

  BONIFACE, ULTRA: Gilbert, Finest Hour, 612.

  216

  TRITON: Erskine, “Naval Enigma: Breaking of Heimisch and Triton,” 180. Some writers use TRITON to mean the four-rotor Enigma, but this is wrong. TRITON carried U-boat messages enciphered in three-rotor Enigma well before the four-rotor machine came into service on February 1, 1942 (see, for example, PG 32137:203 and M.Dv.Nr.443g, P. 4, of 1941).

  220

  Alexander takes over: Good, 5–6; Andrew Hodges, 204, 227–28.

  220

  McVittie: Filby and Howse interviews.

  220

  Kriegsmarine weather cipher: BJ 5/288.

  221

  Archer: Howse and Wylie interviews.

  222

  Admiralty transmitted to Washington: copies in U.S. Navy’s Operational Archives.

  16. When Sailors Look for Leaks

  Details of U-boat communications are from interviews with Meckel, Kuhne, and Wilde; NA:RG 165: Box 727, Folder U-118, Interrogation of Josef Hoeller, Oberfunkmaat, pp. 9, 10, 12, 17–19; SRGN 15993; SRMN-032, 98–99; Hirschfeld, 141–44; Dönitz (trans.), 231, 246.

  The several investigations into German cipher security may be found in RM 7/103 at 38–39, 42, 62 (Stummel’s investigations), PG 34534 (Fricke’s first investigation), RM
7/121:57–61 (his second), and PG 32137 (Maertens’s investigation). Measures to restore or improve security are given in PG 34534 at 143–44, 153, and in MA:M797/47357:47.

  The naval grid and its encipherment are described in Erskine, unpublished study; BdU, KTB, 1.–15.September 1941, Anlage; Hinsley, 2:681: ADM 223/3:259–60.

  The proposals to improve the Enigma are in MA: III M 1006/6:51–55; RM 7/108:45. For the fourth rotor and the thin reflector, see Erskine and Weierud. On the B-Dienst and its successes: Tranow interview; MacLachlan, 77; Bonatz, Deutsche Marine-Funkaufklärung, 80, 86, 103, 105, 174; Bonatz, Seekrieg, 29, 32, 33, 36; Hinsley, 2:634–36; Kahn, Hitler’s Spies, 212–22; Dönitz letter, January 27, 1970.

  231

  “main cipher method”: M.Dv.Nr.32/3 (1941), 2.

  231

  “Equipping with the Enigma”: PG 47006:Bericht über den Nachrichtendienst am 4.3.41.

  231

  Navy monitored, required reports: PG 34455F:i9.Januar 1939, 28.November 1939; MA:M797/47357:50–51, 8. Mai 1941; Kleikamp, 15; PG 47364:26. Mai 1941 and 29.April 1941.

  232

  Prien, Graf Spee: RM 7/103:36, 41.

  239

  5 October 1941: Erskine, “Naval Enigma: Breaking of Heimisch and Triton,” 180.

  239

  U-570: ADM 199/2058:38. BdU, KTB, 5 November 1941, on the surrender of the U-570, has nothing about ciphers.

  240

  Desk IVa: Kahn, Codebreakers, 456, 458.

  241

  “despite great stresses”: PG 32137:186.

  244

  rise in traffic volume: Rohwer, “Ultra and the Battle of the Atlantic,” 429, 432.

  244

  January 1, 1943: Rohwer and Jäckel, 125.

  245

  February 1, 1942: Hinsley, 2:179.

  248

  sixty times better, “unimaginable”: RM 7/121:60.

  17. Blackout ’42

  249

  recover the wiring of the 4th rotor: Hinsley, 2:747.

  249

  cryptanalysts apprehensive: Wylie interview.

  249

  “the picture”: Hinsley, 2:230.

  250

  considerable knowledge: Beesly, 111–12.

  250

  14,000 per month: Hinsley, 2:29.

  250

  radio fingerprinting, TINA: Hinsley, 1:271.

  250

  “working fiction”: Beesly, 113.

  250

  direction-finding: Mitchell interview.

  252

  three TRITON keys: Hinsley, 2:228.

  252

  one of ten, one of three: Rohwer, “Ultra and the Battle of the Atlantic,” 432, 435.

  252

  600,000, 2,600,000: Roskill, War at Sea, 1:618, 2:486.

  252

  seventeen days: Hinsley, 2:228.

  252

  fears grew: Hinsley, 2:168–69, 548.

  253

  “a little more,” “the one campaign”: Hinsley, 2:548.

  18. The George Cross

  Details of the U-559, its cruises, and its captain are from PG 30594; Rohwer, Axis Submarine Successes; NA:RG i65:G-2 Captured Personnel and Material Branch: Enemy POW Interrogation File (NIS-Y): German Prisoners at Byron Hot Springs: Albert Müller, 23881. Details of the Petard, its captain and crew, and the attack on the U-559 are from ADM 199/2060:44–45; ADM 1/14526; Connell, passim, esp. 65–71; Thornton (unpublished), passim. In a letter of October 8, 1989, Connell wrote that he and several other members of the crew of the Petard to whom he has shown this file agreed that some statements in it, made several weeks or months after the sinking of the U-559, confuse this incident with the similar boarding of the Italian submarine Uarsciek. The Petard came alongside the Uarsciek but stayed perhaps a hundred yards away from the U-559.1 have therefore eliminated from my account all references to the U-559’s closing with the Petard.

  255

  U-boats to Mediterranean: Dönitz, 158, 199; Germany, Oberkommando der Kriegsmarine, Lagevorträge, 409.

  255

  “decisive area”: Ibid., 302.

  265

  “It’s out”: Wylie interview.

  265

  “It’s come out”: Monroe interview.

  265

  four-letter indicators: Hinsley, 2:750.

  265

  Beesly thrilled: Beesly, Very Special Intelligence, 152.

  265

  position of fifteen U-boats: DEFE 3:705:ZTPGU 1; Erskine, “Naval Enigma: The Breaking of Heimisch and Triton,” 120.

  266

  sinkings halved: Roskill, War at Sea, 2:486.

  19. Enter the Americans

  Details about interception and direction-finding come from Mitchell interview. Information about the Bletchley bombes is from interviews with Herd, Milner-Barry, Monroe, and Stewart; Payne, 9–16; “Breaking Enigma”; Hinsley, 1:338, 2:748, 750; Welchman, Hut Six Story, 141, 144, 147. Details about Hut 8 and cribs are from interviews with Wylie, Amys, and Hinsley; Deavours and Krüh, “Turing Bombe.” Information about the Hut 4 watches are from interviews with Forster, Ettinghausen, and Eytan.

  The background to the British-American exchange of cryptanalytic information may be found in Hall and Wrigley, 358–63, 375–81; Hinsley, 2:55; Ronald W. Clark, Tizard (Cambridge, Mass.: M.I.T. Press, 1965), 248–71. Cryptanalysis is specifically mentioned in NA:RG 165: War Plans Division 4340: September 9, 1940. The story of the trip of the four American cryptanalysts comes from Rosen interview; Currier, untitled memoir; Weeks letter; SRH-145, 002–004; ADM 199/447:Operation Parcel; ADM 53/114501 January 24–February 6, 1941.

  The operation of the American naval cryptanalysis and its cooperation with the British come from interviews with Joseph Eachus, W. V. Quine and Marjorie Quine, Prendergrass, McMahan, and Bartelmez; Hinsley, 2:56; Beesly, Very Special Intelligence, 108–10; “U.S. Navy Communication Intelligence Organization Liaison and Collaboration 1941–1945,” SRH 197 (October 8, 1945), reprinted in NCVA [Naval Cryptologie Veterans Association] Cryptolog 5 (Winter 1984), 5–11.

  275

  U.S. Army contingent: Parrish, 106.

  275

  6812th, two to three times as many solutions, U-boat cipher: Stewart interview.

  277

  20 percent, 3 percent: Safford, 12.

  277

  exchanging direction-finding: Safford, 4.

  278

  former girls’ school: “Rochefort Affair: Admiral Stone Comments,” NCVA Cryptolog 6 (Fall 1984), 6.

  279

  “The Star of Suez”: SRMN-032,001.

  280

  high-speed bombes; Atha, 332–36.

  283

  daily U-boat summary: W. V. Quine interview.

  283

  naval Enigma read to end of war: Hinsley, 2:751–52, 552. The date of May 24, 1943, at 2:667 should be May 24, 1945 (Hinsley).

  284

  solutions to Knowles: Knowles, 445.

  284

  Secret Room: SRMN-038.

  285

  “were not as smart”: Smith-Hutton, 396–97.

  285

  Convoy & Routing chart: Norgaard interview.

  20. SC 127

  Information on the convoy’s composition, escorts, and routing is from U.S. Navy, Naval Historical Center, Operational Archives, Tenth Fleet Files, Convoy & Routing Section, Convoy Folder SC 127, and from ADM 199/580, supplemented by National Archives of Canada, Record Group 24, Vol. 11335, File C-8280, SC 127. All Allied estimates of submarine locations come from SRMN-033. All U.S. solutions of German naval messages come from SRGN. All information about German intelligence and activity comes from BdU, KTB, under the appropriate dates. Weather conditions are from the log of H.C.M.S. Dundas.

  Food and shipping problems are from Behrens, 201, 312, 328, 331, 334, 342, 345–46; Hammond, 1:261–68, 2:792; Great Britain, Ministry of Food, How Britain Was Fed in War Time, 58–59.

  287

  April 16 sailing details: National Archive
s of Canada, Record Group 24, vols. 12015, 12042.

  287

  92, 111, 29, 50, 95: Morison, 1:410.

  290

  three days behind: DEFE 3.

  290

  U.S. report for April 16: SRMN-033:2074.

  290

  Operational Research: Blackett; Waddington; Schofield, 161.

  291

  63 boats operating: BdU, KTB, April 16, 1943.

  293

  grid bigrams: comparison of SRGN 15945 and DEFE 3:716:131, in which the British message gives the enciphered coordinates and the American message the solved ones.

  294

  no messages solved for Monday: SRGN 16029 is a message of April 18, SRGN 16030 is a message of April 20.

  294

  “Since this position”: BdU, KTB, April 18, 1943.

  295

  Katyn, a German Dunkirk, white hair: [Germany], Reichssicherheitshauptamt, Amt III, Meldungen aus dem Reich, ed. Heinz Boberach (Neuwied: Luchterhand, 1965), Nr. 377.

  295

  In the United States: New York Times, April 21, 1943.

  300

  HX234: Hinsley, 2:568.

  21. The Cavity Magnetron Clue

  303

  “We can no longer rely”: Hinsley, 2:563.

  303

  5 to 10 percent: Rohwer, “Einfluss,” 359.

  303

  “In the Atlantic”: BdU, KTB, May 24, 1943.

  304

  no convoys: Hessler, §301.

  304

  April 18: BdU, KTB, April 18, 1943.

  304

  Maertens exculpated Enigma: RM 7/107.

  305

  regional key nets; RM 7/108:44; BdU, KTB, February 3, 1943.

  305

  new type of radar: Reuter, 113–14.

  305

  “With the exception” BdU, KTB, March 5, 1943.

  306

  “the enemy has”: BdU, KTB, April 27, 1943.

  306

  “For some time”: BdU, KTB, April 27, 1943.

  306

  Maertens, Stummel: Walter Lohmann and Hans H. Hildebrand, Die Deutsche Kriegsmarine 1939–1945: Gliederung, Einsatz, Stellenbesetzung (Bad Neuheim: Podzun, 1956), 3:320, 386.

 

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