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