No single aspect of the Second World War is full of mysticism and speculation as much as ULTRA. Just the mere mention of ULTRA with a campaign brings mythical overtones. As the word implies, ULTRA means something beyond or on the other side of moderation. Yet ULTRA was not a weapon system with phenomenal power. It simply was the code-word for the information obtained through communications intelligence during the war. like other forms of intelligence its significance depended on its timeliness, reliability, and appreciation by commanders. As it will be shown in this volume and its companions, the mere possession of ULTRA intelligence would not be a sole factor in deciding any engagement. This was especially true in the Battle of the Atlantic

The invention and subsequent advancements of radio communications at the turn of the century was especially important for the navies of the world. This new technology allowed naval authorities to maintain command and control of their fleets operating in distant locations. However, this new development could be as much a hindrance as a benefit. As early as the Russo-Japanese War in 1904 it was discovered that monitoring the enemy's radio transmissions could provide indications of its intentions.1 Systems of codes and ciphers were developed as a safeguard to disguise the meanings of the radio messages. Thus, by the First World War the majority of the world's navies employed cryptographic systems to protect their communications from disclosure to their adversaries. Likewise, each navy was motivated to break the security measures to gain advance knowledge of the opposition's intentions.

The extensive operations of the world's fleets during the First World War saw increased reliance on radio for control. This increase in usage allowed one's adversary the opportunity to develop intelligence on naval operations. The British had set the standard in the field of communications intelligence in the naval realm. They had developed an elaborate system of radio direction finding and code breaking forming a reliable source of


intelligence on the enemy. This development of communications intelligence enabled the British to monitor German naval radio traffic with considerable success.

The achievements of the British during the First World War were well noticed by the American navy. In a 1931 review of the decrypting activities of other governments the Americans considered the British navy as the standard to follow.2 The British were successful in breaking German naval codes, had top radio security procedures which defeated German efforts of attack, and, above all, possessed the integrity to preserve the secret of their work during the war. Additional attributes included new methods of communicating with operational units without disclosing their location. Also, the British were the first to develop an office for specifically disseminating codes and ciphers, and they had the administrative capacity to maintain fifty-nine active codes simultaneously. By 1937 the American admiration expanded to the area of recruitment and training of personnel.3 The British methods of attracting high quality personnel was chosen for emulation. Thus, in a somewhat distant manner British efforts in communications intelligence inspired the direction of the American effort in the inter-war period.

Prior to addressing the role of communications intelligence in the Battle of the Atlantic, it would be helpful to review its development in the U.S. Navy. The importance of the Atlantic prior to the Second World War was overshadowed by the threat of the Japanese in the Pacific. The suddenness of war in Europe in 1939 caught the American naval communications intelligence organization off guard. Nevertheless, the American naval organization was able to begin world-wide collection, direction finding and evaluation of communications intelligence as intercepts were obtained. The origin of ULTRA as a concept was not of American origin and was not adopted until collaboration with the British during the war.

The code-word ULTRA was of British origin. The word was used to identify the source of intelligence for those who


had access and need to know. By using this identifying caveat the recipients of the intelligence would immediately appreciate the source as highly reliable. Specifically, ULTRA intercepts were decoded Enigma-generated German military and diplomatic messages sent by radio. Yet this special intelligence had a series of code-words for its designation.4 HYDRO was the first code-word associated with this form of intelligence used by the Royal Navy. Throughout the war Winston Churchill preferred to use the code-word BONIFACE as his designated source of communications intelligence instead of the military-inspired terms. The Royal Navy replaced HYDRO with the word HUSH and by mid-1941 adopted ULTRA as the final caveat.5 The increased collaboration between the British and U.S. navies in the field of communications intelligence necessitated complementary security measures.6

The incorporation of security measures for this special intelligence in the U.S.Navy lacked specific guidance. While the U.S. Navy was involved in communications intelligence since the end of the First World War it did not have formal security measures like the British. There was no adoption of caveats to the security classification until June of 1942.7 The June 1942 a Chief of Naval Operations (CNO) directive established that there should not be any mention as to the origin of the intelligence in correspondence and that either the code-word ULTRA or ZEAL should be used at the beginning of a message.

The incorporation of the new security measures failed to be employed as envisaged by the CNO. The American office


responsible for the origin of much of ULTRA intelligence did not always follow the directive. Correspondingly, Admiralty messages to the U.S. did not begin to receive ULTRA designations until late 1942.8 U.S. naval messages to the Admiralty did not receive ULTRA caveats until January 1943.9 This lackluster employment of the security criteria required more attention within the American navy.

In March 1943 the CNO reaffirmed the needs of security and special handling of communications intelligence. The earlier security directive was superseded and the new policy required all material derived from cryptanalytical means to be stamped either as ULTRA or SUPER in addition to the usual security classification.10 Cryptanalytical means was the method used to break the cryptographic security of enemy radio messages. Any hint of this type of work would naturally cause the enemy to change codes and setback the codebreaking efforts. Inner office correspondence by OP-20-G did not adopt the ULTRA caveat until the spring of 1944.11 Once the formalities of classification management were settled, U.S. and British naval correspondence followed similar guidelines.

The U.S. Navy was deeply involved in the field of communications intelligence since the mid-1920's. This effort was under the supervision of the Director of Naval Communications (OP-20) who oversaw all aspects of collection, evaluation, and dissemination of communications intelligence for the U.S. Navy. The office directly responsible was the "Communication Security Section" (OP-20-G).12 As tensions


began to rise during the late 1930's, OP-2D-G was faced with two threats on opposite sides of the globe. The predominant emphasis of cryptanalytical work was directed towards the solution of encrypted Japanese traffic. This reflected the dominance that War Plan ORANGE had in the navy. The technical advances of the Germans in the Atlantic had reduced the efforts of OP-20-G to that of traffic analysis.13 Up to the reorganization of OP-20-G, following the Pearl Harbor attack, communications intelligence in the Atlantic theater received a low priority.

American naval interest with signal intelligence in the Atlantic theater dates from 1918. In October the Navy installed a rotating loop radio direction finder (D/F) at the Naval Radio Station, Bar Harbor, Maine.14 Five other D/F stations were established along the eastern coast shortly afterwards. Originally intended for tracking German U-boats during the First World/War, these stations came too late. With less than thirty days after commissioning the Bar Harbor unit the armistice was signed in 1918. A newly established New York station was in operation in time for use in the location and guidance of American battleships returning from Europe.15 However, these D/F units were relegated to support duties to aid in the navigation of naval and merchant vessels and not for intelligence activity.

Time and the, lack of attention had a degrading effect on the shore based naval radio direction finders. In 1924 the Navy had 52 medium frequency D/F stations in operation on both coasts. By 1941, 22 remained in commission of which only six or seven were in effective operating condition.16 Most of the sites had deteriorated due to poor maintenance, fire, storm damage and other unexplainable acts. In July 1941, the navy formally transferred custody of these original D/F stations to the U.S.Coast Guard.


The development of high frequency direction finding (HF/DF) operations began in the early 1930's. Originally envisaged in 1933 and amended in 1935 the development of strategic HF/DF sites world-wide was proposed.17 Of the eleven chosen locations, four were to be situated on the Atlantic coast.18 Winter Harbor, Maine, received the highest priority of the Atlantic sites and was operational in early 1935. Yet the first American fix on a foreign vessel by HF/DF came from the Cavite site in the Philippines in late July 1936.19 Despite this accomplishment, the reliability of the HF/DF equipment was poor and an extensive development program was initiated to identify an ideal apparatus for naval service. By June 1938 an advanced HF/DF unit had been installed at Winter Harbor. Despite the placement of new equipment at the East Coast locations, the Atlantic HF/DF group would have only the primary mission of "training" and would be manned "intermittently."20 Finally, by July 1939, the new Direction Finder Policy was promulgated and officially established the Strategic Tracking Organization.21

The end of 1940 saw dramatic improvements to the American naval communications intelligence organization. By December OP-20-G had successfully tracked by HF/DF both German submarines and surface raiders in the Atlantic.22 Training of both enlisted and officer personnel was progressing rapidly. Technical innovations were also being rapidly incorporated into communications intelligence efforts. There was also the strengthening of collaboration with the British against adversaries in the field of communications intelligence.

Organization of the Atlantic intercept and HF /DF capabilities received considerable attention in the spring of 1941. In April the British Admiralty supplied the U.S. Navy with one of their latest Marconi Adcock HF/DF sets for test and evaluation.2323 In May it was decided that all remaining Naval Navigational Direction Finder Stations would be transferred to


the U.S. Coast Guard. The transfer of these sites would provide new opportunities for OP-20-G. J, The growth of HF/DF sites required additional OP-20-G personnel. The maneuver with the U.S. Coast Guard helped ease the personnel crunch at OP-20-G. New sites in 1941 included Greenland; Charleston, South Carolina; and Toro Point, Canal Zone. Two additional sites were projected for 1942 at Cabo Rojo, Puerto Rico and another to be located at either Trinidad or Brazil. Additionally, in May, a continuous watch officer for control of the Atlantic Strategic HF/DF net was initiated. By December 1941 the U.S. Navy had a global strategic HF/DF system in place with centralized control. It consisted of three net control stations (Atlantic, Pacific, and West Coast) that controlled 20 HF/DF sites.

Radio interception gradually supplemented HF/DF as a form of communication intelligence. Site selection for interception operations was similar to that for the HF/DF stations. Bar Harbor, Maine was involved in intercept activities as early as November 1931. The station was subsequently relocated across Frenchman Bay at Winter Harbor in early 1935.24 While the primary concentration of its activities had been diplomatic traffic between Europe and Tokyo it was also well situated for other forms of radio interception.

At some point in 1931, interest was taken to intercepting Russian radio traffic. Eight special Underwood typewriters were ordered to be made with Russian (Cyrillic) type-set keys.25 In 1933 Bar Harbor's activities had "been diverted" from its normal diplomatic interests to concentrate on other topics. At the time the Soviets were becoming more active both militarily and diplomatically. They had been experiencing difficulties with the Japanese in the Far East and were engaged in collaboration in naval affairs with the Germans and Italians. In diplomatic affairs the Soviets had begun treaty negotiations with France, Germany, and several other countries.26 The onset of war in Europe in September 1939 brought about a declaration of national emergency in the United States and a new view of priorities. Intercept reorganization came during the first week of September. Winter Harbor was


relegated to HF/DF only. Interception for the Atlantic theater during this time frame fell upon stations at Jupiter, Florida and Cheltenham, Maryland.27 The missions of these shore based stations would change later in the war with Chatham, Massachusetts replacing Cheltenham as the primary interception site.

Interception of radio communications was also accomplished by American naval vessels. As early as February 1937 American naval vessels assisted in the collection of communications intelligence in Europe. The U.S.S. Hatfield (DD 231), under the guidance of the Director of Naval Intelligence, began intercepting communications and forwarding the material to Washington.28 The Hatfield was anchored at La Rochelle-Pallice and was well situated for intercept operations. However, the radio division personnel lacked formal training in this type of operation. The Commanding Officer requested further guidance in June to ensure proper methods were being employed in the collection effort.29 The Director of Naval Communications responded by establishing the priorities of interception and the required formats of future reports.30 The Hatfield established the standard for European communications intelligence collection that would be followed by others.

The European Squadron, Squadron 40-T, had been in operation since September 1936.31 Both the Director of Naval Communications and the Director of Naval Intelligence appreciated the significance of this new source of intelligence.


The prospective flagship for Squadron 40-T, USS Raleigh (CL 7), was given copies of the work of the USS Hatfield and the guidance furnished by OP-20-G.32 The original purpose of the squadron was to evacuate Americans during the Spanish Civil War. The close proximity of an intercept unit in Europe would ensure more accurate reception of local naval radio communications.

An intercept unit was established with Squadron 40-T with the permission of the Commander, European Squadron.33 The unit and its four radio specialists were established on board the USS Omaha (CL 4) and was designated as Station F by OP-20-G. Operations of Station F commenced on 12 December 1938 with the primary coverage was of German and Italian naval communications.34 The Omaha departed for the Mediterranean in late April 1939 and that Station F would increase the amount of information available on German radio procedures and schedules. Coincidentally, the German naval fleet was deployed to the same area as the European Squadron.

The progress of Station F was steadily increasing but its future was in question. In May 1939 it was decided to let the station exist for one more year. As a result, when the Omaha was relieved by the USS Trenton (CL 11) on 19 June 1939 Station F accompanied the Flag staff. Radio intercept coverage resumed on 10 July aboard the new flagship. The monitoring of German communications had documented the routine procedures and practices of the naval traffic. An abrupt change in the routine was noticed on 28 August 1939, two days prior to the invasion of Poland.35 It was observed that the format of messages changed, transmitter power increased, and a noticeable restriction was enforced on radio procedures. All of the intercepted traffic of Station F was forwarded to Washington for evaluation.

The opening of hostilities in Europe had a dramatic impact on American communications intelligence. By 24 October 1939 it was acknowledged that the Atlantic area had been neglected. OP-20-G declared that the Atlantic Ocean and


the East Coast would now be considered the number one priority.36 Commander Laurance F. Safford, then head of OP-20-G, speculated that Japan might even become a U.S. ally in the oncoming war.37 However,his view would be short lived and not shared by other officers. An American communications intelligence officer in the Pacific observed, in the spring of 1940, that the Japanese had been operating without any fear of opposition at sea.38

Interest by American communications intelligence in the Atlantic and European areas continued to mount. The first indicated liaison of American and British communications intelligence personnel came in the spring of 1940. Two American naval representatives visited the British HF/DF station on the island of Bermuda.39 They had observed British operations, net procedures and the employment of fixed antenna equipment.

A formal, and highly secret, agreement concerning naval communications had been made between the British and American governments in 1937.40 The agreement had been made at the instigation of the British Admiralty and was so secret that only one American officer active duty was aware of its existence. Three hundred fifty copies of a publication covering the complete description of the American communications organizations and procedures were held in the Europe.41 In the event of war the American naval communications representative, would provide the publications to the British.

In October 1940, the Special Naval Observer (SPECNAVO), London, was approached by an Admiralty representative concerning further collaboration in communications


intelligence.42 The British provided information concerning positions, frequency coverage, control stations, and linkages of these stations with the Admiralty. The British requested that the Americans reciprocate the exchange of information. This request was granted and similar information on American communications intelligence activities was sent to London on 20 November.43

Afloat communications intelligence continued to contribute to the European effort. The transfer of Station F was accomplished once more with the arrival of the new commander and his flagship, the USS Omaha. In fact, the new commander of the squadron, Rear Admiral Charles E. Courtney, recently relieved as Director of Naval Communications (OP-20) and aware of the importance of Station F. The transfer of Station F occurred after 5 July 1940 and returned to its collection duties. Primary coverage would now center on Italian naval circuits in the Mediterranean. The ensuing naval battles throughout the summer were covered by Station F and relayed on to Washington. Early in October 1940 Squadron 40T was recalled from duty in Europe due to the increased risk of conflict with the belligerents

The need for more accurate communications intelligence in Europe was being felt by OP-20-G. Previously, the majority of intelligence gained from communications had come from HF/DF and traffic analysis. The rapid growth of intercepts of European messages allowed the Americans to begin a dedicated attack on decrypting this traffic.44 The incorporation of attacking European generated intelligence into OP-20-G seems to have begun around July 1940. A two-person European branch was added to the cryptanalytical section.45

The interest in European traffic intensified by October 1940. Losses of merchant shipping to U-boats reached a new high in October. The continued reliance of radio communications by the U-boats represented a weakness that


could be exploited. The communications intelligence situation was made worse when the Japanese made drastic changes to their main naval cipher systems in December.46 OP-20-G had no immediate solution to the Japanese changes and recovery was not near. At the time there were only five officers and two civilians working in the cryptanalytical section.47 The threat from the V-boats seemed to be increasing as the months passed. Thus, OP-20-G was forced to address European cipher system. Work was divided up in the office with the hope that a break would be possible.

Two separate sections for attacking European traffic were created.48 The first, headed by Agnes Driscoll centered on German naval systems. The second, headed by Lieutenant Lee W. Parke, concentrated on Italian naval systems. There was some prior work on German systems, but it was of no avail. Commander Safford hoped that the employment of Mrs. Driscoll in the effort would produce favorable results.49

In early 1941 the collaboration between American and British navies intensified. In January the United States decided to give the British one of the PURPLE machines for breaking Japanese diplomatic message traffic. The machine was escorted by four military officers; two were from OP-20-G.50 The Americans hoped the British would reciprocate the offer by giving a copy of the German ENIGMA machine cipher. Instead the British exhibited their efforts against the ENIGMA and presented them with all the keys that had been recovered and


a paper analog of the cipher.51 The American mission also was given a copy of the latest British HF/DF unit for evaluation.52

The American contingent returned and applied what they had learned from the British to their work against the European ciphers. However, the work was time consuming and showing little progress. Further collaboration continued on the only truly dependable intelligence resource available at the time: HF/DF. By July the reproduction of British codes and ciphers for HF /DF reporting was being carried out for joint use.53

In the spring of 1941 sought to improve the interception effort with the Atlantic sites. In March direct commercial teletype service was authorized for the Winter Harbor and Amagansett radio intercept facilities.54 This development allowed the stations to forward intercepts immediately to Washington upon receipt. While the primary emphasis was on Japanese diplomatic traffic other "messages of unusual nature appearing to be of sufficient importance to warrant attention" would also be forwarded.55 The result was improving coverage of radio circuits and minimizing delays in getting the intercepts to the cryptanalysts.

Establishment of coverage by the radio intercept stations was promulgated in the fall of 1941. Atlantic stations served as four of the five major intercept facilities on the continental United States.56 The primary and secondary missions of the Atlantic stations were:

Station Primary57 Secondary
W (Winter Harbor) Italian Naval Axis Diplomatic
M (Cheltenham) German Naval Axis Diplomatic
G (Amagansett) Diplomatic None
J (Jupiter) Diplomatic None


Atlantic Strategic HF/DF Net by December 1941


Within two months of the Pearl Harbor attack the first major reorganization of the Code and Signal section of the U.S. Navy was made since its beginning in First World War. What followed was the complete detachment of communications intelligence and communications security from one another.58 It was determined, following a comprehensive study by Commander Joseph N. Wenger, assigned to the war plans section of OP-20-G, that a more centralized and highly coordinated control authority be established for communications intelligence.59 An additional emphasis on increased communications was stressed for information correlation and interpretation. The proposals of Wenger were accepted and adopted following a reorganization conference with the Director of Naval Communications, Admiral Leigh Noyes. 'The reorganizations' was as follows:

Office Mission   Officer in Charge
OP-20-G Communication Intel Cryptanalytical Cdr. J. N. Wenger
OP-20-K Communication Intel Combat LCdr. L. W. Parke
OP-20-Q Cryptography   Capt. L. F. Safford
OP-20-U Security Section   LCdr. R. L. Densford

By 24 June 1942 OP-20-G had evolved into an efficient and well organized office. When a break finally came with the German ciphers in December 1942 a further reorganization took place within OP-20-G.60 The need existed for a separate division for handling intelligence acquired on the Pacific and Atlantic theaters.

The creation of the "Atlantic Section" within OP-20-G did not develop until January 1943.61 Prior to this Atlantic communications intelligence correlation was conducted by the office primarily concerned with Pacific theater matters. It is known that the Atlantic Section was functioning well prior to


the TORCH landings in North Africa in November 1942.62 A small section was established in early 1942, but the increase of traffic overwhelmed the limited staff. Two officers from the Pacific Section of OP-20-G were reassigned to the Atlantic section to assume watch over non-German Atlantic activities.63 Due to the delays, involved in processing the intercepts, the Atlantic Section was not a key element in direct support for the TORCH landings. Nevertheless, the experience obtained aided in the clarification of organizing the office to support current operations.

While the need existed for proper correlation of Atlantic communications intelligence the development of such a unit was slow in going. The initial head of the informal Atlantic Section was Lieutenant Willard "Van" O. Quine in the fall of 1942. The Atlantic Section, formally known as OP-20-GI-2, was officially established when its designated officer in charge, Lieutenant Commander Bernard F. Roeder, assumed his duties after returning from the Pacific in January 1943. From that point on, the Atlantic Section served as the correlation and dissemination branch for all Atlantic related communications intelligence.


List of Abbreviations

ASDICUnderwater sound location device
BAMSBroadcasts for Allied Merchant Ships
CBMCubic meter
CINCCNACommander in Chief, Canadian Northwest Atlantic
CINCWACommander in Chief, Western Approaches
CESFCommander, Eastern Sea Frontier
CMSFCommander, Moroccan Sea Frontier
CNOChief of Naval Operations
COMINCHCommander in Chief
COMNAVEUCommander, Naval Forces Europe
CRTCathode Ray Tube, television screen
CSPCode and Signal Publication
CVEEscort aircraft carrier
D/FDirection Finding
FOICFlag Officer in Charge
GAFGerman Air Force
GC&CSGovernment Code and Cypher School
GNAGerman Naval Attache
GNATGerman Naval Acoustic Torpedo
GSRGerman Search Receiver
H/FHigh Frequency
JNAJapanese Naval Attache
M/FMedium Frequency
MPAGerman naval D/F divisions
MPHSGerman naval D/F main stations
M/VMerchant Vessel
NEMOAmerican code name for captured U-505
NOICNaval Officer in Charge
ONIOffice of Naval Intelligence
RAFRoyal Air Force
RIPRadio Intelligence Publication
RFPRadio Finger Printing
SISItalian Naval Communications Intel Organization
SKLGerman Naval High Command
SPECNAVOSpecial Naval Observer
TINARadio Transmission Characteristics Intel
T-VZaunkonig acoustic torpedo
VL/FVery Low Frequency
WWGerman Weather Messages


Table of Contents ** Next Chapter (1)


1. Mario de Arcangelis, Electronic Warfare: From the Battle of Tsushima to the Falklands and Lebanon Conflicts (Dorset, England: Blandford Press, 1985), 11-12.

2. Records of the National Security Agency, J. S. Holtwick, Jr., "Naval Security Group History to World War II: Appendices," SRH-355, Part 2, 22-28, National Archives, Washington DC, Record Group 457, (hereafter cited as NSA, RG 457, with filing designations).

3. Ibid., 264-66.

4. Warren F. Kimball, ed. Churchill & Roosevelt: The Complete Correspondence, Volume I, Alliance Emerging. (Princeton: Princeton University Press, 1984), 214-15.

5. Ibid.; Patrick Beesly, Very Special Intelligence. (Garden City, NY: Doubleday and Co., 1978), 105. HUSH seems to have prevailed longer in the US. This may be due to the somewhat sluggish collaboration effort. Examples of "HUSH Secret" can be seen in US documents in 1943.

6. For more information on the cooperation between the two navies in communications intelligence, see Bradly F. Smith, The Ultra-Magic Deals and the Most Secret Special Relationship (Novato, CA: Presidio Press, 1993.)

7. Records of the Secretary of the Navy/Chief of Naval Operations (Secret-Confidential), Admiral King letter to Commander in Chief, US Atlantic and Pacific Fleets and Commander Southwest Pacific Force, Folder A6-2/A8, Box 287 (A6-2--A6-2(12)), National Archives, Washington DC, Record Group 80 (hereafter cited as SECNAV/CNO (SC), RG 80, with filing designations).

8. NSA, RG 457, SRH-236, Part 1, "US Navy Submarine Warfare Message Reports: Admiralty to COMINCH 24 May 1942-31 December 1942," 215.

9. NSA, RG 457, SRH-208, "US Navy Submarine Warfare Message Reports: COMINCH to Admiralty 3 June 1942-31 May 1943," 37.

10. NSA, RG 457, SRMN-018, "US Navy (OP-20-G) West Coast Communications Intelligence Activities, Policies and Procedures 20 June 1942-26 December 1943," 7.

11. Apparently the US Navy did not begin classifying its documents "ULTRA Top Secret" until April 1944. "Top Secret" as a security classification was not employed in the US until March 1944. See NSA, RG 457, SRMN-054, Part 1, "OP-20-GI Special Studies relating to U-boat Activities 1943-1945," 95-108.

12. Designations for OP-20-G were:
October 1917March 1935Code and Signal Section
March 1935March 1939Communication Security Group
March 1939October 1939Radio Intelligence Section
October 1939February 1942Communication Security Section
February 1942July 1946Communication Intelligence Section

13. NSA, RG 457, SRH-264, Joseph N. Wenger, "A Lecture on Communications Intelligence," 14 August 1946, 12.

14. NSA, RG 457, SRH-355, Part 1, 77.

15. Ibid., 77n.; L S Howeth, History of Communications-Electronics in the United States Navy. (Washington: Government Printing Office, 1963), 265.

16. NSA, RG 457, SRH-355, Part 1, 79.

17. Ibid., 174.

18. These were to be Winter Harbor, Maine; Jupiter, Florida; Cheltenham, Maryland; and either Puerto Rico or the Virgin Islands.

19. NSA, RG 457, SRH-355, Part 1, 186-87.

20. Ibid., 303.

21. Ibid., 333-35.

22. Ibid., 409.

23. Ibid., 424.

24. Ibid., 124, 139.

25. Ibid., 100. Two were initially ordered in 1931 and another six in 1933.

26. John Erickson, The Soviet High Command: A Military-Political History 1918-1941. (Boulder, CO: Westview Press, 1984), 332-33.

27. NSA, RG 457, SRH-355, Part 1, 337.

28. Records of the Office of Naval Intelligence (1929-1942), Commanding Officer (DD-231) letter to Chief of Naval Operations (Director of Naval Intelligence), DD-231/A8(C-17), dated 1 March 1937, Folder A6-1/EF, Box 124 (A6-1/EF13--A6-2/EF13), National Archives, Washington DC, Record Group 38, (hereafter cited as ONI, RG 38, with filing designations).

29. ONI, RG 38, Commanding Officer (DD-231) letter to Chief of Naval Operations (Director of Naval Intelligence), DD-231/A8(C-187), dated 8 June 1937, Folder A6-1/EF, Box 124 (A6-1/EF13--A6-2/EF13).

30. The primary target was German naval communications and a secondary target was Italian naval communications. See ONI, RG 38, Director of Naval Communications letter to Director of Naval Intelligence, OP-20-GX (SC)A6-2/A8, serial 2815, dated 23 June 1937, Folder A6-1/EF, Box 124 (A6-1/EF13--A6-2/EF13).

31. Samuel Eliot Morison, History of United States Naval Operations in World War II, Volume 1, The Battle of the Atlantic, 1939-1943. (Boston: Little, Brown, and Co., 1964), 16.

32. ONI, RG 38, Chief of Naval Operations letter to Commander Squadron 40-T (USS Raleigh), OP-16-B12, A6-1/EF(6-23), serial 1733, dated 13 July 1937, Folder A6-1/EF, Box 124 (A6-1/EF13--A6-2/EF13).

33. NSA, RG 457, SRH-355, Part 1, 310.

34. Ibid., 327.

35. Ibid., 338.

36. Ibid., 343.

37. Ibid.

38. Ibid., 356.

39. Ibid., 368. These were Lieutenant (Junior Grade) J M Leitwiler and Chief Radioman H. Kidder.

40. SECNAV/CNO (SC), RG 80, OP-20-G letter to Director of Naval Intelligence, serial 040620, dated 16 January 1940, Folder A6--A6/A1-1(Oct 40), Box 223 (A4-3/QSI-A6-2).

41. One hundred fifty copies were kept with the Naval Attache in London and 200 copies were kept with the Commander, European Squadron.

42. SECNAV/CNO (SC), RG 80, SPECNAVO, London letter to CNO, serial 31 dated 17 October 1940, Folder A8-3/EF13 (Sep-Oct 40), Box 230 (A8-3-A8-3/EF13).

43. SECNAV/CNO (SC), RG 80, Director of Naval Communications letter to Director of Naval Intelligence, serial 084720, dated 20 November 1940, Folder A8-3/EF13 (Sep-Oct 40), Box 230 (A8-3-A8-3/EF13).

44. The higher the volume of messages of a particular code or cipher system the greater the likelihood of breaking that system.

45. NSA, RG 457, SRH-355, Part 1, 375-76.

46. Edwin T. Layton, "And I was there" (New York: William Morrow and Co., 1985), 78.

47. Ibid. At the time of the Japanese change the office had to attack the German ENIGMA. The Japanese Naval Attache machine cipher, continued work on JN-25 operational code, and also provide assistance to the Army with its attack on the Japanese diplomatic code.

48. NSA, RG 457, SRH-355, Part 1, 400.

49. Agnes Driscoll was most noted for her work on Japanese code and cipher systems. She had been working on the JN-25 code since November 1939. Once assigned to the German section she had no further involvement with Japanese systems. Editor's interview with Albert J. Pelletier on 16 March 1994.

50. In addition to escorting the PURPLE machine the naval officers had an additional mission. They were to observe, in detail, the British HF/DF organization and equipment. This had been by the direction of Commander Safford. Upon the officers' return to American only Safford was briefed about the British HF/DF efforts. Editor's interview with Robert Weeks on 28 February 1994.

51. Editor's interview with Prescott H. Currier on 10 February 1994; David Kahn, Seizing the Enigma: The Race to Break the German U-boat Codes, 1939-1943 (Boston: Houghton Mifflin Co., 1991), 235-37.

52. Smith, 58.

53. NSA, RG 457, SRH-355, Part 1, 430.

54. Ibid., 410.

55. Ibid., 421.

56. Ibid., 430.

57. Stations G and J were covering only the Rome, Berlin, Tokyo circuits transmitting to each other and to South American capitals.

58. NSA, RG 457, SRH-279, "Communications Intelligence Organization 1942-1946," 1-2. The new sections were designated OP-20-G and OP-20-Q respectively.

59. Ibid., 4-14; NSA, RG 457, SRH-403, "Selections from the Cryptologic Papers Collection of Rear Admiral J N Wenger, USN," 4; NSA, RG 457, SRH-355, Part 1, 461.

60. NSA, RG 457, SRH-355, Part 1, 463.

61. The OP-20-G "Atlantic Section" should not be confused with the COMINCH "Atlantic Section" which was the primary consumer of OP-20-G-A's efforts.

62. Jeffrey K. Bray, ed., Ultra in the Atlantic, Volume VI, Appendices. (Laguna Hills, CA: Aegean Park Press, forthcoming), Appendix 17.

63. The two officers were Allan R. Molten and John S. Adams.

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