title graphic

Appendix 13

Case of Presumed and Confirmed Compromise
1943 - 1945


Listed below are German messages which are believed or are known to have contained information derived from decryption intelligence. The compromised Allied source (dispatch and system) is given where known. This list can not be regarded as exhaustive even for U-boat traffic, but it does include all cases suspected and examined for compromise by the Atlantic Section of OP-20-G. The list has been checked against British (GC&CS) investigations insofar as records of these investigations were available.

It will be noted that in nearly all cases the German messages were sent as Offizier messages. That ULTRA intelligence available to the Germans should have been disseminated in the cipher system reserved for matters of unusual importance and secrecy is natural enough, but the possibility remains that use may have been made of decryption intelligence in the normal or common U-boat traffic. (The plain enigma system) Hence in a few instances, messages of particular interest have been included in the list even though these messages were not sent as Offizier.

Note on compromise of merchant signals:

Members of the Italian communications intelligence organization stated that merchant signals were easily read and that there was no difficulty in obtaining a supply of documents from sunken ships. References to "Merchant Navy Code" appeared in Japanese Naval Attache traffic in November 1942 when the German communications intelligence organization turned over photographic copies of the documents to the Japanese, together with other relevant material. (See Chapter VI, para 6 of Volume III.) Little information, however, is available through U-boat traffic on direct use of merchant signals before 1944. Of the confirmed cases which appear at the end of this Appendix, the case recorded for March 1944 aroused considerable anxiety, for the Allied dispatch involved contained a U-boat estimate which was based on ULTRA intelligence. (For a discussion of this point see Chapter VI, para 12 of Volume III.)

The references to "SA-#" can be found in SRMN-54 (Part I).

-- 181 --


German Dispatch Source


December 1942

No Offizier messages are available for this month. As a possible case of compromise the following is recorded:


"para 3. Object: surrounding a convoy going southwest, which is expected on approximately the 23rd, RM 31 (AL 31, 53°15'N - 22°45'W)"





No satisfactory accounting for this information could be found in the Convoy & Routing files for this convoy, ON 154. The U-boats involved were groups Spitz and Ungesturm. The resulting operation was the most successful convoy operation in December.


January 1943

1) 1108/7

Offizier N

According to B-Service it has been established that an English unit was detailed on 3 Jan to patrol Neumann's (U-117) last provisioning area. Purpose may be: either search for survivors (of sinking by group Spitz), or to chase submarines on basis of D/F's from the numerous messages sent by Neumann's provisioning group, or both. Your attention is once more called to most extensive radio silence during provisioning., avoid unnecessary transmitting.



British Naval Code, General Table Area 1 (K 1). Time lag 4 days.
(Enemy Intel Report #52)

2) 2216/7

Offizier L

To: Bruns (U-175)

Occupy next the sector west-north-west of ET 38. (Freetown). Presumably convoys leave there for ed 99 (Trinidad) in a 10 to 11 day rhythm. Next departure possible on 8 January. Passage points of a December convoy were:
ES 3696 (08°51'N - 19°57'W)
ER 1515 (09°27'N - 35°03'W)
EP 1352 (10°09'N - 50°03'W)

Another convoy on 17 December was in latitude of ET 38 (08°15'N - 13°10'W "B"), course 295, speed 8.



Precise source unknown.


-- 182 --


German Dispatch Source

3) 1349/9

Offizier O

To: Group Falke

English passenger ship Capetown Castle from AK 8224 (53°33'N - 33°25'W) to AL 6134 (56°15'N - 19°25'W) will pass the line presumably on 9 January. You may leave position in line only upon sighting the ship.





Precise source unknown.

4) 1156/25

Offizier S

To: Reeder (U-214)

1. Tanker convoy route is suspected from LP 49 over IZ 22 and 89 as well as XO 37 and FX 9690.
2. Straggler route probably runs over naval squares 4770 and 6910 of the large square west of disguised square FF as well as over FF 05 eastward.

(Interpretation of positions:
LP 49 is probably ED 99: 10°55'N - 30°50'W
IZ 22 is probably DS 72: 20°50'N - 34°45'W
XO 37 is probably DG 87: 27°10'N - 30°50'W
FX 9690 is DH 4690: 30°27'N - 20°06'W
FF 05 is probably DS 55: 22°40'N - 32°05'W
(DR) 4770: 21°27'N - 44°03'W
Squares west of FF probably (DR) 6910: 22°03'N - 36°51'W)




Precise source unknown.

February 1943

1) 2312/10

Offizier I

To: All U-boats on Series 1

Position of apparent attack area of American U-boat was square PF 5854 on 9 February (PF 5854, no information)




Precise source unknown. This case was studied in some detail but without results. The Germans presumably had reference to one of U.S. subs based on Rosneath, Scotland (Squadron 50) and the position must have been one of 3 possibilities off Western France. The logs of USS Shad, Herring, Barb, and Blackfish were examined but gave no leads that could be followed.


-- 183 --


German Dispatch Source

2) 1754/14

Offizier W

To: All U-boats on Series 3

Group Rochen including Luis (U-504) on 16 February 1200A be in reconnaissance line from JH 8285 to SJ 7785. Course 285. Day's run 150 nautical miles. Sequence: Bargsten (U-521), Markworth (U-66), Becker (U-218), Schwandtke (U-43). Other boats in sequence in which they set out from Czygan (U-118). Eastbound convoy expected beginning 17 February. Another little patrol line will be north of AI 64 (or north of you in AI 64).

(Interpretation of positions:
JH 8285 is probably CE 8285: 36°45'N - 30°06'W
SJ 7785 is probably DG 2785: 32°15'N - 30°06'W
AI 64 is probably CE 64: 38°50'N - 27°40'W)





Precise source unknown.
Convoy UGS 5

3) 1731/18

Offizier M

To: All U-boats on Series 4

Steamer Coulgorn left Freetown 12 February for Saldanha Bay. Passage points GG 27, GH 9570. Speed 9.

(GG 27: area of 24°11'S - 00°33'W GH 9570: 29°15'S - 10°33'W)




Precise source unknown.


4) 2322/18

To: Group Neptune

Last disposition order rescinded. On 20 February 0000(A) be in new patrol line from DE 7438 to 5269. Westbound convoy is expected on the 20th.

(DE 7438 = AK 2438: 59°45'N - 30°24'W
 DE 5269 = AK 0269: 56°45'N - 30°12'W)



Convoy ON 166, which lost 15 ships to Ritter-Knappen. It will be noted that these changes in patrol lines were made in less than 1/2 hour. It is difficult to account for the sudden re-disposition of U-boats (they had been expecting an eastbound convoy, HX 226) without assuming some good last minute intelligence. First ON 166 diversion (CINCWA Secret 1001Z/17) could account for U-boat disposition. Like the other Allied traffic concerning this convoy, it was sent in Combined Cipher #3, table S. (See SA 13-C)


-- 184 --


German Dispatch Source


To: Group Ritter

Order for period up to now cancelled. On February 20th at 0800 (A) be in patrol line from square IZ 5299 to UK 9423. Westbound convoy expected.

(IZ 5299 = AK 0299: 56°27'N - 30°12'W
UK 9423 = AK 9423: 52°45'N - 30°05'W)



Oelrich (U-92), Höltring (U-604), Walkerling (U-91) and Zurmühlen (U-600) will form group Knappen and occupy on 20 February 0000 (A) patrol line from XI 9293 to 9684. Westbound convoy is expected on the 20th. Turn on Diana 19 February 0800(A).

(X19293 = AK 9293: 53°03'N - 28°05'W
XI 9684 = AK 9684: 52°03'N - 27°25'W)


5) 2310/27

Offizier N

To: Group Rochen

Operation with 6 boats including Rasch (U-106) is intended, on a westbound slow convoy, from 2 March on, in area naval square 90 of the large square west of RL. On 26 February 2000(A) convoy was in CB 9979, course about 260, speed 8.

(Naval Square 90 is DF 90: 28°03'N - 36°03'W
RL is DG
CB 9977 is DH 4979: 29°2TN - 20°45'W)




FOC Gibraltar's daily situation report, 2000/26 February, in Combined Cipher #3, table S, Area 1. Time lag 1 day. (Enemy Intel Report #52) This case illustrates difficulties of compromise investigations. FOC Gibraltar's dispatch was not available in the Convoy and Routing files. COMNAVEUR also sent a convoy situation report for 2000A/ 26 February which included GUS 4 (COMNAVEUR Secret 261639 to all US Commands concerned with etc.) but it was sent in ECM. It was not thought that ECM had been compromised.


-- 185 --


German Dispatch Source


March 1943

1) 1304/10

Offizier Y

Keller (U-130)
Henke (U-515)
Emmermann (U-172)
Rüggeberg (U-513)
Rasch (U-106)
Sturm (U-167)

Be in positions at 1000(A) 12 March in reconnaissance line from naval square (CD) 8381 (36°51'N - 39°50'W) of the large square west of disguised square FX (CE) to naval square (CD) 2221 (42°51'N - 41°02'W) of the large square west of disguised square VV (CE). Course 270, speed of advance 5 knots. Do not arrive earlier than ordered. Radio silence except for (or, until) tactically significant reports. Eastbound convoy expected beginning 12 March.


2) 1847/14

To: Raubgraf

Discontinue operation. Head for square UT 49 (BC 34: area of 49°40'N - 42°15'W) at high speed.


To: Group Raubgraf in the order
Bertelmann (U-603)
Kapitzky (U-615)
Zurmühlen (U-600)
Schamong (U-468)
Strelow (U-435)
Walkerling (U-91)
Manseck (U-758)
Gräf (LJ-664)
Uphoff (U-84)

Take positions at 1200(A) 15 March in patrol line from square DI 1383 (AJ 9883: 51°15'N - 42°05'W) to ER 5081 (BC 3581: 49°27'N - 40°55'W). Object: To get hold of eastbound convoy to which further groups can later also be detailed.



These messages concern U-boat formations for convoy HX 229. At the conclusion of the operation German Command called it the "greatest success yet against a convoy." Both the original route and the diversion route recommended by Admiralty were sent in Combined Cipher #3, table M (CESF Secret 041704Z and C&R Secret 131602Z). While neither message was sent in Offizier setting the circumstances lead one to presume that cipher compromise was involved. (See SA 13-B, case 2)


-- 186 --


German Dispatch Source
3) 1119/18

Offizier S

To: Trinidad U-boats

Convoy with speed of 13 was in naval square DT 6222 (23°57'N - 21°15'W) on 13 March at 2000(A). It is proceeding via EG 1145 (18°09'N - 44°03'W), EF 4176 (15°09'N - 52°03'W) and EE 7476 (11°33'N - 60°09'W), at which point-according to dead reckoning-it should arrive about 21 March.




Combined Cipher #3, table S. Convoy TO 2. GCCS recorded two dispatches as sources: FO Gibraltar and FOC WAF reports, 2247A/10/2 and 1402/ 13/3. Time lag 9 1/2 - 5 days. (Enemy Intel Report #52). Another candidate would be NOIC Gibraltar's Secret 2242A/10/3 to USS Roper and Decatur, time lag 7 days 12 1/2 hours, although NOIC Gibraltar's dispatch does not account for convoy position as given for 2000A/13. (See SA 13-B, case 2)

4) 2005/20

Offizier D

To: All U-boats on Series 1

A convoy steering course of 250 to 270 is expected to be in YH 3625 at 0900(A) 21 March. Pich (U-168) is to be there at the time mentioned, and to wait a few hours. If convoy is not found, sweep on small zags for the courses mentioned. On sighting convoy, without attacking, shadow for group Seeteufel.

(YH 3625 probably AK 2125: 60°45'N - 32°48'W)

(Presume same message as TOO 2022/20/3 reported in ZIP/ZGU/24)




"Almost certainly based on Special Intelligence, of which the precise source was not confirmed."
(ZIP/ZGU/24) The convoy was probably ON 173.

April 1943

1) 2259/11

Offizier I

To: All U-boats on Series 3

Position of English steamer Manadalay on 9 April was approximately naval square FK 60 (area 09°45'S - 26°39'W) and it is proceeding over FK 3290 (06°45'S - 26°21'W) and FE 4310 (00°27'S - 17°57'W).




Precise source unknown. (Enemy Intel Report #52) Original routing message (RO Baries Confidential 272245 March) was sent in F.S. SHIPCON Argentina Area 1543/1544A. It is not known whether this information was subsequently relayed in combined cipher.
(See SA 13-B, case 3)


-- 187 --


German Dispatch Source
2) 1909/12 (1902/12/4 according to AIP/ZGU/24)

Offizier F

To: All U-boats on Series 3

Southbound convoy will be in naval; square FK 4850 (13°39'N - 18°33'W) on 13 April 0800(B), speed about 7.5.




Precise source not confirmed. (ZIP/ ZGU/24) Convoy was probably OS 45.
(See SA 19)

3) 1315

Offizier A

To: All U-boats on Series 3

Presumably a floating dock on 3 April at 2200(B) in naval square EP 4879 (05°09'N - 51°09'W) speed 2. On 11 April at 2200(B) in FB 1566 (01°03'N - 42°27'W), course 085, speed 4.5, apparently going to Freetown.




Combined Cipher #3, table M. From dispatches sent on 3 April and on 10 April (2011Z). (Enemy Intel Report #52)

May 1943

1) 1432/3

Offizier N

Southbound convoy going via Freetown was by dead reckoning in about EK 4590 (14°15'N - 18°15'W) on 2 May at 0800(B), speed about 7.5. Probably floating dock on 3 April at 2200(B) in EP 4879 (05°09'N - 51°09'W - vicinity French Guiana coast), speed 2, on 11 April at 2200(B) in FB 1566 (01°03'N - 42°27'W), course 085, speed 4.5, probably for Freetown. With a speed of 3.5 can be expected there beginning 4 May. All naval squares.



The convoy was probably OS 46.
(See SA 13, case 1)


-- 188 --


German Dispatch Source
2) 2307/7

Offizier G

To: Groups Rhein and Elbe

An expected convoy was in LD 2684 (BC 7684: 43°57'N - 48°25'W) on 6 May 2330. Precise course not known, but approximately eastward, speed 9.3.




Combined Cipher #3, table S, page 14, 1.8. W6 Secret 062130Z to CINCCNA. Time lag 23 hours, 28 minutes. Convoy HX 237. (See SA 13, case 1)

3) 0025/9

Offizier K

To: Group Rhein

The expected convoy, according to sure report, is further south and further ahead than assumed. A patrol line must therefore be drawn up by 2000(B) on 9 May extending from OG 2927 (BD 7927: 43°33'N - 34°55'W) to VA 9154 (CE 4154: 39°45'N - 35°02'W). Maintain radio silence.




Could have come from any one of several dispatches sent between 5 and 8 May in Combined Cipher, table S. (See SA 13, case 2)

4) 0952/11

Offizier X

To: Group Drossel

Eastbound Clausen (U-403) convoy will be in naval square 9552 (44°21'N - 27°15'W) at 1600(B) May 11.




CINCWA Secret 090901Z May in British Naval Code #3, Auxiliary Vessel System SP 02358/44. Time lag 2 days. (SA 13, case 3.) ZIP/ZGU/ 24 states that Combined Cipher #3, table S, area 1, was the source. Enemy Intel Report #52 lists a dispatch TOO 0901/9/5 in Auxiliary Table Area 1 (I 1) as source. Convoy HX 237.

5) (The following is inserted on basis of GCCS Enemy Intel Report #52, although there is no record of such a message here: 7/11 "Unidentified steamship in tow on 9/5 in 36°19'N - 32°32'W.")
  Combined Cipher #3, table S, area 1, from 1034B/9/5/43. Time lag 1 1/2 days.

6) 2241/19

Offizier M

Sidney Star left Montevideo 12 May for Clyde via naval square FK 4391 (08°39'S - 30°57'W) and DS 4212 (15°51'N - 36°03'W); will arrive (Clyde) 1 June. Speed 14.5.



Routing dispatch was RO Montevideo Confidential 112105Z May sent in HCM 61. Diversion dispatch was C&R Confidential BAMS 152056Z in Ship Pad 539. Information repeated in Combined Cipher #3? (See SA 13, case 7) Precise source unknown. (Enemy Intel Report #52)


-- 189 --


German Dispatch Source
7) 1654/20

Offizier V

1. Steamer left Rio May 11, via 14°S - 26°W, 01°S - 15°W. Speed 9.5; due in Freetown May 24.
2. Steamer left Rio May 13 via 14°S - 26°W, 01°S - 16°W, speed 8.5; due Freetown May 26.



Steamers were SS Marija Petrinovic and Empire Arund respectively. Routing dispatches Rio Confidential 112324 and 122352 May, both to Convoy Route and both in HCM Mk II 1533B. Enemy Intel Report #52 attributes German information to dispatches of 11 and 13 May (not identified) in Combined Cipher #3, table M.

8) 2214/21

Offizier H

To: Group Mosel

The expected convoy was in square UW 7682 (BC 2782: 49°27'N - 43°45'W) on 20 May 1700(B). It is to be in square CG 6148 (ED 1148: 50°27'N - 38°15'W) on 21 May 1700(B), and is to head from there for square IJ 3581 (AK 8581: 52°09'N - 33°25'W) speed 9 - 9.5.




Combined Cipher #3, table S, area 1. Straggler rendezvous positions, convoy HX 239. CINCCNA BAMS 2011310 in Incom SP 02406 pad 332 only dispatch containing this information in Convoy & Routing files. (See SA 13, case 14) Enemy Intel Report #52 lists 1714492 and 201224 in Combined Cipher #3, table S, as containing same information.

9) 1252/22

Offizier I

Position of large convoy bound for Freetown was plotted 22 May 0800(B) approximately naval square EK 1335 (17°33'N - 17°21'W).



Precise source not confirmed. (ZIP/ ZGU/24) Convoy was probably OS 47. (See SA 19)


-- 190 --


German Dispatch Source
10) 1252/23

Offizier Q

Auxiliary Cruiser Bulolo was in naval square ES 1720 (08°33'N - 27°33'W) on 4 May. On 15 and 18 May an unrecognized English unit on patrol.



Precise source unknown.

11) 1106/24

Offizier B

Johansen (U-569), Rendtel (U-641), Christophersen (U-228), Baltz (U-603), BrQnning (U-642), Hunger (U-336), Krech (U-558), Engel (U-666), Hause (U-211), Struckmeier (U608), Trojar (U-221), Marbach (U-953), Presel (U-951), Ziehm (U-232), Strelow (U-435), Reichenbach (U-217) head at once for naval square 87 of the large square west of TT (area of CD 87: 35°15'N - 42°05'W). Square must be reached by May 31, 2000(B). U-boats arriving with less than 50 cbm are to report posit and fuel on hand at once.


Offizier Sophie

To: Group Trutz

1. Action is planned against westbound convoy, expected in the (patrol) line from 1 June to 6 June. Speed 8 - 8.5.
2. Beginning 1 June, an eastbound convoy is expected approximately in area of Struckmeier's (U-608) position (about 33°N - 43°W) consisting of their attendant tankers protected by escorts...



Combined Cipher #3. COMINCH 211944Z to CESF and NOB Bermuda. Time lag 61 hours, 22 minutes. Convoy is Flight 10. (See SA 13, case 10)

12) 2032/27

Offizier P

An American submarine was in AK 5445 (55°03'N - 35°15'W) on 24 May at 2100(B) proceeding to its patrol area near AK 7657 (52°15'N - 36°25'W). Another American submarine was on patrol on the 24th at 2100(B) near AK 7182 (53°03'N - 39°15'W). Both submarines are submerged during the day. All naval squares.



Combined Cipher #3, table S, area 1. COMINCH Confidential 241705Z US Submarine Notice. Time lag 3 days. (See SA 13, case 6)


-- 191 --


German Dispatch Source
13) 1905/29

Offizier C

A straggler from an eastbound convoy is proceeding over following positions: naval square AJ 9355 (55°15'N - 40°45'W), AK 1895 (55°27'N - 34°00'W)



Combined Cipher #3, table M. CINCWA 272014 (repeated in Admiralty Liverpool 272015Z BAMS. Time lag 44 hours, 50 minutes. Convoy HX 240.
(See SA 13, case 5)

14) 1456/30

Offizier W

On 28 May English steamer Lombardy received orders to deviate from present course and to head, via 03°25'S - 31°42'W, for 06°26'S - 31°28'W.



Combined Cipher #3, table M? Diversion, Convoy & Routing BAMS Confidential 281502Z, was sent OUTCON 434. GCCS assumes message must have been re-enciphered in #3, table M, for Brazilian area. Enemy Intel Report #52.
(See SA 13, case 9)

15) 1531/31

Offizier D

On evening of 29 May an American submarine was on patrol within 20 miles from naval square AJ 6891 (53°57'N - 41°55'W) another one in naval square BD 1321 (50°57'N - 34°55'W) submerged by day, on surface at night.



Combined Cipher #3, table S. COMINCH Confidential 291613Z US Submarine Notice. Time lag 45 hours, 18 minutes.
(See SA 13, case 8)

16) 1917/31

Offizier X

Position 31 May 0800 of convoy running to the South Atlantic by way of Freetown, was, according to dead reckoning, naval square EK 7995 (10°39'N - 17°21'W) speed about 9.






Probably from Combined Cipher #3, table M, but not confirmed. Enemy Intel Report #52. Convoy probably was WS 30. (See SA 19)


-- 192 --


German Dispatch Source

June 1943

1) 1021/1

Offizier H

To: Group Trutz

From today noon on, count also on westbound convoy. When you sight it, operate on it.




Probably from daily situation report in Combined Cipher #3. Convoy was GUS 7A, whose original route was sent in ECM 38 (CMSF Secret 240300Z). (See SA 13, case 10)

2) 1102/7

Offizier I

According to dead reckoning, convoy bound for Freetown area was approximately in naval square ET 2640 (09°09'N - 15°15'W) at 0800 7 June.



Precise source not confirmed. (ZIP/ZGU/24) Convoy was probably OS 48. (See SA 19)

3) 2159/7

Offizier D

To: Kamecke (U-119)

(Results) so far: The British steamer Alva, 1584 tons, has run into your minefield and sunk.




Combined Cipher #3, table S. CINCCNA Confidential 032323Z. Time lag 92 hours, 30 minutes. (See SA 13-1, case 2)

4) 1202/8

Offizier S

English passenger ship Orion on 5 June in naval square GZ 7971 (45°47'S - 06°34'E), enroute from Durban to Freetown, ETA 13 June; speed about 20. A second steamer proceeding from Durban to Lagos; ETA 16 June; speed about 15.



Precise source unknown.

5) 1211/8

Offizier W

To: All U-boats on Series 4

On 8 June a convoy coming from Durban is expected in Capetown. Unknown steamer from Durban to Buenos Aires was in naval square GR 5633 (33°39'S - 18°26'E) on 5 June 2200. Days run 156 miles.




Precise source unknown.


-- 193 --


German Dispatch Source
6) 1729/8

Offizier F

American submarine Hake on 5 June patrolling area of naval square AK 7263 (53°21'N - 37°05'W); submarine Haddo in naval square 8787 (51°03'N - 34°55'W).



Combined Cipher #3, table S. COMINCH Confidential 051606Z US Submarine Notice. Time lag 71 hours, 30 minutes. (See SA 13-1, case 1)


Offizier N

U.S.A. submarine Herring was in naval square AK 6588 (54°39'N - 28°45'W) on 5 June; course not known; proceeding submerged by day.



Same. Time lag 77 hours.

7) 1557/10

Offizier W

To: Kamecke (U-119)

Steamer Highland Count, tonnage unknown, sunk in about naval square BB 7583 (44°03'N - 63°05'W). Presumably ran into your minefield.




No record of ship Highland Count. If error for SS Halma, then probably from Combined Cipher #3, table S. NSHQ Confidential 040335Z to Admiralty, info CINCCNA and COMINCH

* * * * * * * * * *
Combined Naval Cipher #5 Introduced on 10 June 1943
* * * * * * * * * *

8) 1319/25 (June)

Offizier D

To: Staatz (U-508)

Four steamers received instructions on 10 to 14 June to proceed via naval square FF 5138 (00°33'S - 08°21'W).




Source unknown.
(ZIP/ZG/252, Appendix III)


-- 194 --


German Dispatch Source
1) 1946/1

Offizier Y

To: Simmermacher (U-107)

The following American declared area has been announced: Sea area between 37°08'N and 37°38'N, 74°48'W eastwards to the 200 meter line.




This case was investigated with the assistance of COMINCH but precise source was not found.

2) 1626/16

Offizier P

To: Group Leuthen

1. Operation on westbound convoys only from 21 September on, convoy "ONS" is expected, from 23 September on, convoy "ON." Both westbound. Possibly late ...

(Following the Leuthen operation on convoys ONS 18 and ON 202, U-boat Command continued throughout September and early October to arrange his groups on the basis of convoy intelligence. These messages were not in Offizier settings. They are too numerous to quote but are listed here for reference.)




Convoys ONS 18 and ON 202. This German message led to reopening of compromise question with British, in view of convoy dispatches in Combined Cipher #5, table M. British concluded compromise of #5 not involved in this case.

1115/22/9 to Barber (U-220), giving information on eastbound convoy (SC 142).

2336/23/9 to Leuthen, indicating plans for operation against eastbound convoy (HX 257).

1457/24/9, plans changed, operation to be against westbound convoy (ON 203).

1645/24/9 formation of Rossbach (for ON 203 operation).

1102/25/9 to Rossbach, concerning delay in convoy arrival.

1701/26/9 to Rossbach, further on convoy speeds and estimated time of arrival. (ONS 19 now added).

2054/27/9 to Rossbach
2055/28/9 to Rossbach
2232/1/10 to Rossbach

  Each of these cases were checked carefully. Although the results did not show clear signs of compromise, COMINCH and Admiralty were currently informed of the fears which continued to be entertained. British believed German convoy intelligence could be accounted for by traffic analysis and low grade sources.


-- 195 --


German Dispatch Source
1) 1855/2

Offizier S

To: Group Rossbach

1. You may definitely count on the arrival in patrol line of ONS convoy on or before 3 October; and on the arrival of ON convoy beginning 3 October. Hence continue sharp lookout.
2. Cautious enemy comments on the 'Leuthen convoy' confirm that the enemy has been dealt a telling blow.




As above.
Convoys were ONS 19 and ON 204.

2) 1742/8

Offizier R

To: Schrewe (U-537)

8 October at noon, westbound convoy in AL 37 (area of 57°45'N - 18°25'W); 9 October in AL 15 (area of 58°40'N - 25°35'W). Naval squares.




Source unknown.
Convoy was ON 205.

3) 2239/19

Offizier E

Eastbound convoy will be in naval square AK 97 (51°27'N - 30°15'W "B") at noon 20 October. No operation; count on strong aircraft. Take advantage of chances that are offered.



Combined Cipher #5, table S. Convoy HX 261. C3 Secret 181659 to CINCWA. Time lag 28 hours, 41 minutes. (See SA 13-5, case 1) GCCS concurred.

4) 1205/22

Offizier H

1. Hungerhausen (U-91), Hille (U-762), Wenzel (U-231), Mahrholz (U-309), Struckmeyer (U-608), Dobbert (U-969), Witzendorff (U-267), Von Davidson (U-281), Poel (U-413), Boddenberg (U-963), Lamby (U-437), Reich (U-426), Heller (U-842), Popp (U-552), Jaschke (U-592), Boehmer (U-575), Gänge (U-226), Von Lehsten (U-373), and Weber (U-709), will make up group Siegfried, and will take positions in patrol line in this order on 24 October at 1200(A) from square Green TC 1928 (probably AJ 9928: 51°39'N - 40°45'W) to square Green YY 5938 (probably BC 3938: 48°57'N - 38°45'W).



Precise source unknown.
Convoy was HX 261.


-- 196 --


German Dispatch Source
2. Eastbound convoy is expected beginning 24 October, evening.
3. More will follow.

November 1943

1) 2300/14

Offizier K

To: Group Eisenhart

1. Slow northeast bound convoy which is running approximately via square Green IW 69 (area of BD 49: 45°08'N - 34°45'W), 5350 (BD 3350: 50°33'N - 25°45'W) and Green AW 8610 (AL 6610: 55°21'N - 17°15'W) is placed tonight by dead reckoning approximately in Green SP 48 (BD 28: 48°45'N - 31°45'W).




Combined Cipher #5, table M. Partial recovery of CINCCNA's diversion dispatch Secret 100606Z to escorts. Convoy SC 146. (See SA 13-6, case 1)


Offizier R

To: Group Eisenhart

2. Convoy referred to in Offizier message of 14 November (2300/14, quoted in part above) is probably further south than has been assumed. Escorting aircraft were located at noon today approximately Green SP 02 (BD 82: area of 45°09'N - 31°45'W) and 03 (BD 83: area of 45°09'N - 30°1SW). Course of the convoy from this square apparently to Green LZ 91 (AM 71: area of 53°15'N - 15°15'W). HX convoy steering northeast is in the same area.




The HX convoy was HX 265. HX 265's diversion had also been sent in #5, table M. As far as known, however, this Offizier did not involve further compromise. (See SA 13-6, case 1)

March 1944

1) 1839/30

To: Herwartz (U-843)

Report upon crossing latitude of square Blue AB 88 (FS 38: area of 16°03'S - 18°33'W):
1. Fuel
2. Position at 1300A/30/3.
3. If, when, and where you were observed by enemy before that date.



SP 2272/29. COM 4TH Fleet 281843Z BAMS to BYMS 2141, BYMS 221. "Enemy submarine estimate for 301200Z 1 southbound eastern half of area 01 degrees north 25 degrees west."
(See SA 13-10)


-- 197 --


German Dispatch Source

April 1944

1) 2213/22

Offizier H

To: Hänert (U-550) and Wittenberg (U-856)

Convoy and independents are traveling via Green square NY 8922 (CA 3922: 41°03'N - 68°30'W), then 8379 (3379: 42°03'N - 68°46'W). Today they are in about Green square FQ 93 (CB 43: area of 39°45'N - 64°54'W "B"). Speed about 9.




SP 2388/682.
CESF 211941Z BAMS. Time lag 24 hours.
(See SA 13-11)

August 1944

1) 1802/10

Offizier B

B-report: on 8/8 Commandant American Eastern Sea Frontier ordered 8 allied merchant ships to set navigation lights at night.



SP 2272/31.
CESF 082019Z BAMS 2A. Time lag 44 hours.
(See SA 13-14 and supplement)

2) 1949/24

Offizier X

Allied merchant shipping was warned on 15/8 of an obstruction in approximately naval square BB 7764 (43°21'N - 64°25'W). Our assumption: torpedoed steamer. If this is correct, U-boat concerned report when opportunity occurs.



SP 2272/32.
Admiral Halifax Confidential
151330Z BAMS.
(See SA 14-14)

September 1944

1) 2021/2

Offizier F

On 1/9 Commander American Eastern Sea Frontier sent 4 independents the order to proceed direct from 74°20'W to Cape Cod Canal, then via Long Island Sound to Port of Destination, New York.



SP 2272/31.
CESF Confidential 010511 to 3 British ships. Time lag 37 hours, 10 minutes.
(See SA 13-14)


-- 198 --


German Dispatch Source

January 1945

1) 2326/19

Offizier M

Outbound convoy was to be in naval square AM 9496 (52°03'N - OS°35'W) at 2200 today.



Precise source unknown. No reply received from British in answer to 20-G's query. Convoy probably OS 105/KMS 79.

2) 1816/20

Offizier X

According to B-report, rendezvous for stragglers of outbound convoy is at 2000/20/1 in naval square BF 1257 (50°27'N - 09°25'W).



-- 199 --

Compromise of CSP 953

Case of the blockade runner Rio Grande, sunk by TF 41, 4 January 1944.

On 8-9 December 1943, blockade runners received the following instructions in "Alle" messages 60, 61, 62:

  1. Aircraft or warships challenge merchantmen with 2 letters which change daily. Answer consists of 3-flag signal and international call sign. 3-flag signal changes about every 5 days. Details of changes are not known for either call or answer. 3-flag signal also possible by blinker. Aircraft to be shown name plate outside bridge. In connection with radio communication exchange the ports of departure and of destination and dates are frequently requested.
  2. Since there are no available data on secret call-signs (2-letter challenge, 3-flag signal answer) it is of course possible for the blockade runners to imitate 2nd part of radio communication procedure; however, the secret 3-flag signal must be intentionally hoisted in an unclear manner to be illegible. The challenge NNJ used by warships is no longer practiced, although it has not yet been officially recalled.
  3. Use international call signs of assigned cover-ship. In case scuttling is unavoidable, when transmitting distress signal use enemy secret call sign assigned by radio.

When the Rio Grande was intercepted she attempted to send an RRRR distress signal on 500kcs., using the encoded call sign of the SS James Lykes. The suspicion of CSP 953's compromise which was voiced by COM 4TH Fleet was confirmed by the Atlantic Section. An examination of CSP 953 indicated that the Germans must have had a rather old edition of this publication, for the challenge procedure NNJ was discontinued 1 November 1942. (See SA 13-8)


Table of Contents
Previous [Appendix 12]  *  Next [Appendix 14]

Transcribed and formatted for HTML by Rick Pitz, HyperWar Foundation