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Home , Arthur Zimmermann, Room 40, Zimmermann Telegram

UNCLASSIFIED Cryptologic Quarterly

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In 1917, as dragged on in Europe, of the Zimmermann telegram was the greatest a neutralist President Wilson and a mostly apa­ cryptologic triumph of the First World War. thetic American public wanted little to do with the European conflict. In fact, Wilson had just won reelection under the slogan, "He kept us out of war." However, one supremely significant event early in that year would change the attitude of the entire country toward the war in general and toward in particular. That event was the publication of what came to be known as the Zimmermann Telegram, so named because its author was , imperial Germany's foreign minister. In it, Zimmermann secretly proposed to , then hostile to the , an alliance with Germany in which the Germans would provide Mexico \A.rith ample supplies that the Mexicans would be free to use to reconquer , , and . He further suggested that the Mexican president invite Japan, nominally an Allied nation but of great strategic concern to the United States, to Getm

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It was immediately clear that the telegram Mexican cover story, which Page accepted, to was of inestimable value in finally drawing the explain their acquisition of the telegram, thus United States into the war on the Allied side, a hiding their reading of American message traffic. long-time British objective. Still, there were prob­ Page telegraphed President Wilson with the news lems to be solved before the message could be on , setting in motion a chain of shared with the United States government. First, events in the United States that completely Room 40 was one of the British government's altered the nation's perception of German war darkest secrets. Its existence as the source of the intentions. compromise had to be concealed from the Germans. Likewise, the British needed to conceal As the British had requested, the United from the Americans that they had been reading States government did not reveal the source of American traffic, a touchy issue in that the United the telegram when it allowed the Associated Press States was a neutral country. Third, the telegram to publish it three days later. In fact, a cover story still contained a few gaps that might lead the was devised in which the United States claimed Americans to question its authenticity or actual that it had obtained the telegram itself but could meaning. Hall hit upon an ingenious idea that say no more out of concern for the lives of the per­ addressed all three issues. Using a contact in the sons involved. To support this story, the govern­ Mexico City telegraph office, he was able to obtain ment retrieved from the Washington office of a copy of the enciphered message that had been Western Union the coded original from forwarded from the German embassy in Ambassador von Bernstorff to the German Washington. This version had been sent using embassy in Mexico. This was sent to London code 13040, since the embassy in Mexico did not where, using keys provided by Room 40, an offi­ hold code 0075. As an older and less sophisticat­ cial of the United States embassy deciphered the ed code, the British had recovered most of it and message. This allowed President Wilson to state were able to read virtually the entire text, allow­ truthfully that he had obtained the Zimmermann ing them to fill in remaining gaps. In addition, as telegram and its deciphered version from his own a forwarded message, the telegram had been people, thus blunting the argument of many paci­ given a new date and header information by the fists that the message was a fake supplied by Washington embassy. Use of this version would Great Britain or France to inflame American allow the British to convince the Americans that opinion. The story was widely accepted in the message was obtained in Mexico and lead the Congress and the country, and war was declared Germans to suspect the same. Room 40's role little more than a month later. However, as is evi­ would therefore be concealed. dent from the following translation of the official German report that erroneously pointed the fin­ Because Germany had just declared unre­ ger at an unknown traitor, the critical roles of stricted submarine warfare and the United States Room 40 and cryptology in bringing about this had broken off diplomatic relations as a result, momentous event remained secret. Great Britain held the telegram for more than two weeks, hoping that it wouldn't be needed to prod It is very probable that without the German the United States into war. However, when noth­ foreign minister's message to the Mexicans, some ing happened, on February 22 the British deliv­ other circumstance such as mounting American ered the Zimmermann note to American ambas­ casualties and commercial losses as a result of sador Walter Page, who greeted it with outrage. unrestricted submarine warfare would have even­ The British told him that they had no objection to tually drawn the United States into the war. There its publication but requested that Great Britain can be no doubt, however, that this inevitability not be revealed as the source. They used the was hastened greatly by the deciphering of the

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Zimmermann Telegram, clearly the greatest cryp­ American ambassador [in ] with the tologic coup of the First World War. request that he telegraph it to the State Department to be passed on to the Imperial e1nbassy in Washington. To the inquiry of the [Investigation Report] ambassador regarding what the dispatch con­ tained, he was told that it dealt with the Entente's Berlin, April 4, 1917 response to President Wilson and contained The instructions for the Imperial envoy in instructions to [German ambassador to the Mexico, according to which he should suggest to United States] Count von Bernstorff for his per­ the president of Mexico an alliance with Mexico sonal information. The American ambassador and Japan after the possible outbreak of war with received the dispatch from the Foreign Office on the United States, were enciphered with lottery January 16 at 3 P.M. and forwarded it immedi­ code 0075 without the use of a secret key and ately via the American en1bassy in Copenhagen. attached as no. 158 to telegram no. 157 for the By 7:50 it had already been transmitted by Imperial ambassador in Washington that dealt the main telegraph office there. The State with submarine warfare and was marked top Department delivered it to the Imperial embassy secret. At the opening of telegram no. 157 the date on January 19; it was immediately deciphered at "January 16" was also enciphered; no. 158 con­ the embassy. Telegram 158 was enciphered with tains no date. The coded text was delivered to the code 13040 and telegraphed to the Imperial

English text: Original text: Telegramm No. 1. Ganz geheim. Selbst entzi(fem. Berlin. Jan. 19. 1917. Wir beabsichtigen am 1. Februar uneingeschriinkten On February 1 we intend to begin submarine Ubootkrieg zu beginnen. Es wird Versucht werden, warfare without restriction. In spite of this it is our Amerika trotzdem neutral zu halten. intention to endeavour to keep the United States Fur den Fall, daj!, dies nicht gelingen sollte, schla­ neutral. If this attempt is not successful, we pro­ gen wir Mexico mit f olgender Grundlage Bundnis pose an alliance on the following basis with Mexico: That we shall make war together and together vor; Gemeinsame Kriegfilhrung, gemeinsamer make peace; we shall give general financial sup­ Friedensschluf3. Reichliche finzanzielle port, and it is understood that Mexico is to recon­ Unterstiltzung und Einverstiindnis unsererseits,da.13 quer her lost territory of New Mexico, Texas and Mexiko in Texas, Neu Mexiko, Arizona frilher ver­ Arizona. The details are left to you for settlement. lorenes Gebiet zurilckerobert. Regelung im einzelnen You are instructed to inform the President of Euer Hochwohlgeboren uberlassen. Mexico of the above in the greatest confidence as Euer pp. wollen Vorstehendes Priisidenten streng soon as it is certain that there will be an outbreak / \ geheim eroffnen, sobald Kriegsausbruch mit of war with the United States, and suggest that the Vereinigten Staaten feststeht und Anregung hinzufil­ President of Mexico shall on his own initiative com­ gen, Japan von sich aus zu fortigem Beitritt einzu­ municate with Japan suggesting the latter's adher­ laden und gleichzeitig zwischen uns und Japan zu ence at once to this plan, and at the same time vermitteln. offer to mediate between Germany and Japan. Please call to the attention of the President of Bitte Priisidenten darauf hinweisen, daj!, rilck­ Mexico that the employment of ruthless submarine sichtslose Anwendung unserer U-boote jetzt warfare now promises to compel England to make Aussicht bietet, England in wenigen Monaten sum peace in a few month [sic]. - Zimmerman. Frieden zu zwingen. Empfang bestiitigen. Zimmerman.

English ancl German versions ofthe clecoclecl Zimmermann Telegram (signature clroppecl seconcl n for telegraphic purposes)

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Embassy in Mexico; the telegram arrived there on disseminated by the Associated Press was, in sub- January 19. On February 5 a second set of instruc- stance, correct. tions was sent from Berlin as telegram no. 11 via a different route to the Imperial embassy in Mexico. In it the first set of instructions was mod­ ified to say that the discussion of the question of an alliance should begin immediately rather than after the outbreak of war. This telegram also arrived properly at the embassy.

On March 1 the Associated Press put out a report from its Washington correspondent, according to which a copy of the instructions of the Foreign Office to envoy von Eckardt [in Mexico City] was in the possession of the United States government. The instructions had been sent via Count von Bernstorff to Mexico. The president was already in possession of the docu­ ment when he broke off relations with Germany. The report contains a translation of the text that Count von BemstotfF was purportedly in the hands of the president. (Getmc:in c:imbc:issac\ot to the United Stc:ites)

In the version made public the city designa­ A Havas [sic] report from Washington on tion Berlin is added, and for the date, the day the March 2 states that simultaneously \-\Tith the telegram was sent from Washington and arrived Mexico note Count von Bernstorff had received in Mexico is given. At the opening the words "No. an order to take steps to disable German ships in 1. decipher yourself' and at the end the words American ports; it would even seem that the "acknowledge receipt" are left out. In the text it ambassador had received very detailed instruc­ reads "general financial support" instead of "gen­ tions to make the war quite impossible for the erous financial support"; it reads "it is understood United States in case it declared war on Germany. that Mexico is to reconquer her lost territory in Texas, New Mexico, and Arizona" instead of According to a later report of the Stockholm "agreement on our side that Mexico reconquer Telegraph Bureau, the American government is previously lost terr~tory in Texas, New Mexico, supposed to possess documents according to and Arizona." · which the German government, on January 17, directed Count van Bernstorff to take steps to dis­ In response to an inquiry in the Senate, able machines in ships lying in American ports at J. Secretary of State Lansing said that the govern­ the same moment that diplomatic relations ment could guarantee that the "Zimmermann let­ would be broken. ter" was genuine; however, out of concern for the safety of certain persons whose lives could be News was spread by associates of Sir Francis endangered, it was necessary to keep secret how Oppenheimer, commercial attache at the British the letter came into its hands. Further, Snawson embassy in the Hague, that the Mexican dispatch [sic] announced in the Senate that the president had gone via Holland; from there one could fol­ had authorized him to say that the text as it was low its trail into the hands of the German envoy. After the dispatch had been taken away from the

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German messenger or agent, it was an easy task therefore have been unknown to it up to that for the American State Department to decipher it time. Otherwise, the American government with the help of the key placed at its disposal by would also have taken timely steps to prevent the the British government. disabling of our ships.

There are several conceivable ways in which b. The possibility remains that the American the American government could have come to government obtained the code later. In this know of the Mexican dispatch. It could: regard the Stockholm Telegraph Bureau's report indicates that the American government possess­ 1. have known the code 0075 that was used for es a document according to which the German transmission to Washington; government directed Count von Bernstorff on January 17 to take steps for the disabling of 2. have known the code 13040 with which the German ships. Telegram no. 157 dealing \vith the telegram was further forwarded to Mexico; submarine war actually contains the concluding passage: 3. have received the text itself through trea­ son. Finally, I remind you of preparations for the thorough disabling of German I. The lottery cipher 0075 has been in use steamers. You are responsible for see­ since the middle of July 1916 by the missions in ing that the necessary word is passed Vienna, Sofia, Constantinople (these three with at the proper moment by secure means teletypes), Bucharest, Copenhagen, Stockholm, so that no German steamer falls into Bern, Lugano, the Hague, and Christiana, as well foreign hands in a usable condition. as at headquarters and the Reich chancellery. The cipher with its secret key was sent to Washington In the Stockholm report the date is given in the cargo submarine Deutschland and reached incorrectly. The ciphered text of telegram no. 157 there on November 3, 1916. contains the date January 16. Further, the ques­ tion is raised whether the American government, a. The assertion, also appearing in German if it knew that we made use of its ambassador as newspapers, that the American embassy in an intermediary for the transmission of the Berlin was in possession of the cipher secrets is Mexican dispatch, wouldn't have exploited this obviously false. Had the ambassador been able to against us in its parliament and with the public. read the teA't of the telegram, presumably he Certainly it would be possible that it kept quiet would not have forwarded it, but instead would about this because it wanted to keep from the have telegraphed the contents to Washington. Entente the fact that it transmitted telegrams for However, as we know, he has not sent any us whose contents it did not know. If the telegram from Berlin that dealt with the contents American government knew our code 0075, how­ of our telegrams. It is just as unlikely that in ever, then the Mexican dispatch would have been Washington one could have known the codes at made public \vith the date January 16, and not the time the telegrams arrived, otherwise the January 19. On the other hand, the report that telegram would not have been delivered to the Count Bernstorff simultaneously received embassy. We know besides that the Washington instructions for the disabling of German ships government was surprised by the announcement does not offer sufficient support that the of submarine warfare on January 31. The con­ American government knows the code. tents of telegram no. 157, which gives the day for the commencement of submarine warfare, must

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II. The embassy had the directive to forward embassy for the omission of this security meas­ to the mission the instructions intended for ure, since the Foreign Office also used code 13040 Mexico by secure means. Perhaps sending an without secret key for the encryption of the official as a courier to Mexico could have been instructions going to Mexico when it was the considered. However, this would have attracted intention to send them via cargo submarine to attention. Also, the route of travel was unsafe and America and to send them from Washington tele­ ) ,. slow; e.g., the trip by legation secretary von graphically to their destination. Schoen had lasted two weeks. Besides, the instructions were marked as "Telegram no. 1." At the embassy in Washington there was a Therefore, there can be no objection that the directive to convert all ciphered telegrams to embassy believed itself obligated to choose Mexico and within the United States to words telegraphic means. They provided for the com­ using the ABC Code and to send them to the tele­ munication with Mexico using three codes: no. graph office. This was done for reasons of econo­ 5950, no. 13040, and in addition the Navy my, since otherwise not every group but every Communications Book with secret key. As every­ digit would count as a word for purposes of pay­ one knows, code 5950 was compromised and was ment. However, the conversion also had a certain left in use for unclassified messages only. In order significance for code security in that it was not to make it usable again, at the behest of the Code immediately apparent that one was dealing with Bureau of the Foreign Office, the embassy agreed an enciphered telegram. According to telegram upon a secret keying procedure with all posts in no. 13 from Mexico A.S. 1226 the conversion of America that possessed this code, i.e., with the the telegram of January 19 doesn't seem to have consulates in the United States and with the mis­ been done. Embassy staffer Kunkel, who person­ sions in Central and South America. For this ally worked on the encryption, "believes" he arrangement code 13040 had been used. The :remembers that it left Washington in digits plus Code Bureau regards the procedure as good. The ABC Code. It arrived in Mexico in digits only. It is mission in Havana, however, had given the improbable that a :re-conversion should have embassy its opinion that even in this form code taken place at one of the telegraph offices. That 5950 would not be usable for confidential mes­ could only be done for the purpose of decipher­ sages since the keying procedure was too trans­ ing, and then the perpetrator would certainly parent. It is the Navy's wish that the Navy have been too careful to expose his attempts in Communications Book should be used for naval such a clumsy way. It is more probable that purposes only. Moreover, the embassy had Kunkel is mistaken. received a telegraphic message from East Asia, according to which the Navy code was supposed Code 13040 had been in use since 1912 in to be compromised. On the other hand, it was not Washington and New York, Havana, Port au known to the embassy, either through its own Prince, and La Paz, and since 1907-1909 in the experience or through communications from other missions in South and Central America. In Berlin or other posts, that code 13040 was to be the case of a lot of enciphered material the mean­ considered compromised. Therefore, the ing of a more or less large part of the code can be embassy could envision sufficient security for deduced. It is, however, improbable that the secure transmission with the use of this code. American government should have succeeded in Certainly it could have increased security by con­ deciphering the telegram on the basis of code verting the ciphered digits using the Navy secret materials known to it or provided to it by the key whose confidentiality had not been lost by the English secret service. Also speaking against such compromise of the Communications Book. an assumption is the fact that the text made pub­ Nevertheless, no rebuke can be directed at the lic by the American government is without gaps,

UNCLASSIFIED Page 49 UNCLASSIFIED especially that the names Arizona (four groups) great interest to the American government were and Texas (two groups) are reconstituted in it. sent, are known to the American government.

The American government could, however, At the general consulate in New York, where have come into possession of the code itself or the codes were safeguarded under triple lock, the obtained a copy or photo of it. This could have circle of persons who had access to the codes was happened at any place where the code is found. A smaller. Besides the consulate administrator, this misappropriation of the code has not been consisted of the three vice consuls and consulate reported by any of these places. The consulate in secretary Bern. Consulate secretary Georges, who Guyamas in Mexico, where a break-in is sup­ was originally supposed to return to Germany, posed to have occurred, did not possess the code. then however remained behind \vithout authori­ In Washington and New York all codes were zation, was never involved in code work. It can be burned under supervision after diplomatic rela­ considered out of the question that he should tions were broken. Indications of forcible entry have come into possession of code 13040. into the workspaces or forcible attempts to open the code cabinet have never been noted either at Finally, it is definitely improbable that the the embassy or at the general consulate. American government possesses code 13040, for Nevertheless, safeguarding of the codes in then the text of the Mexico dispatch would cer­ Washington was not especially secure; they were tainly have been made public v.rith the serial located in an older cabinet that was locked only number and notations "decipher yourself' and with a combination lock that was already some­ "acknowledge receipt," as well as with the serial what worn out. The combination had not been number of the Washington embassy and the sig­ changed since 1902. When a combination lock is nature of Count Bernstorff, because in so doing well worn, even a nonspecialist, if he's lucky, can its genuineness would have been made even more correctly dial the combination by feel. It also believable from the very beginning. Further, it wouldn't have been difficult in the summer, when should be borne in mind that code 13040 has the embassy was in the countryside and only very been used for many secret messages, among them few personnel remained behind in Washington, for an exchange of telegrams between Mexico and to slip into the chancery spaces, remove code New York regarding the delivery of equipment for 13040 from the code cabinet, photograph it, and the wireless receiving station in Mexico. It can be put it back again. Code 13040 was located in assumed that if the American government knew Washington during the summer in 1915and1916. of these telegrams, they would have now made them public. In addition, one must consider that one of the officials could have betrayed the code. At the III. It is more probable that the text of the embassy 12 mid-level officials had access to the Mexico dispatch was betrayed. codes in addition to court councilor Sachse's son, who worked as an assistant clerk for a year and a a. The Imperial envoy in Mexico considers it half until the fall of 1916. Should one of these peo­ out of the question that the dispatch should have ple have betrayed the code, it would be striking become known through treason or indiscretion in that this code, and not also the lottery codes, Mexico. Speaking against this possibility is espe­ especially code 0075, was chosen. However, as cially the fact that telegram no. 11 to Mexico, elaborated above, it should not be assumed that which directs the immediate implementation of the American government possesses code 0075; the instructions in the event of war given in also, there is no basis for believing that the other telegram no. 1 and accordingly was of particular­ codes, in which many telegrams and mail codes of ly great interest to our opponents, has not

Page 50 UNCLASSIFIED UNCLASSIFIEDllFOR Ol'l"lelAL l:ISE 9Nb-Y Cryptologic Quarterly become known. Both telegrams were deciphered by significant in order to be able to verify the message a legation secretary and were not read by chancery through comparison with the enciphered telegram officials. The original ciphered texts were burned that had been sent. immediately by the legation secretary and the ashes were scattered. Until they were ordered burned, the The American side asserts that the government deciphered versions of both telegrams were secured already possessed the text at the time that diplo­ in a new steel safe in legation secretary Magnus's matic relations were broken. It is not very likely bedroom which is located in the chancery building. that it should have quietly held onto it for so long. One would sooner be inclined to believe that the b. In Washington, six or seven officials had State Department would have made it public worked on the deciphering of telegram nos. 157 and immediately after receiving it. Then one would 158. Afterward, the embassy councilor had directed come to the view that one of the officials who that talking about them, even within the chancery, remained behind in America is the perpetrator, or would not be permitted. However, all mid-level that if the perpetrator was among the departing officials with perhaps the exception of comt coun­ officials, he would have left negotiations with the cilor Sachse, who was sick, and embassy staffer American or English agent to an accomplice, "'Jjth Kiihn, knew of the Mexico dispatch; one of them instructions to sell the dispatch only after a certain read through the deciphered document once again amount of time had elapsed. It would certainly also a week later. The deciphered document - a carbon be possible that the treason took place earlier and copy doesn't seem to have been made - was filed to deflect suspicion, a delay in making the docu­ unsealed in the same file as, and in fact directly ment public was a condition of the betrayal. Of behind, the telegram no. 157 that contained the course the State Department would have violated concluding passage about the disabling of German this agreement when it let it be known that it was ships. The filing cabinet in which this file was already in possession of the dispatch at the time secured was accessible to all middle-level officials that diplomatic relations were broken. Supporting of the embassy, i.e., 12 persons. The deciphered ver­ the idea that treason is involved is Lansing's decla­ sion of the Mexico dispatch was destroyed in the ration in the Senate that he could not make more first few days of February, apparently on February detailed statements about the acquisition of the dis­ 1. In the time from January 19 to February 1 it can patch without endangering the lives of certain per­ be established that each of these officials, with the sons. That doesn't have to mean someone who is in exception of court councilor Sachse, Dr. Edler, and Germany or on the way there. It is just as likely that Seibert, were alone and unobserved in the chancery Lansing had in mind that German retaliation ·could for a long period of time. At any rate, this was the also strike the perpetrator in America. case during midday duty,, perhaps evening duty as well. Each of them could therefore have copied the It should be clearly emphasized that for all offi­ dispatch. The perpetrator would then have either cials on whom suspicion could fall from this point sold the copy or a translation to a foreign agent or, on, the best evidence is given by their superiors as without negative intentions, have given it to an well as that officials who have been interviewed acquaintance who for his own part betrayed it. The declare it to be out of the question that one of their dispatch is also so short that someone with a good colleagues could have committed such an act. memory can certainly remember the text after one reading. The perpetrator could have communicated /signature/ the final section of telegram no. 157 at the same time. In so doing he would have erroneously given the date as January 17. This date was of no special interest, while the date of the Mexico dispatch was

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(U is a member of the Naval Reserve Security Group Devens, assac usett r rves as the assistant ~-in-ctiar9e of the unit's detachment.I r L__Jhas been a member ? t e ava eserve for eleven years and spends two weeks each summer working at NSA. His most recent a~signment was to the Center for Cryptologic History. Prior to joining the Naval Reserve, he spent eight years on active duty, most of it with the Naval Security Group. As an enlisted man and officer, LCDR I ~erved on board the USS Mississippi, performed tem- porary duty assignments on board the submarines USS L. Mendel Rivers and USS Sea Devil, and served as the er tologic officer on board the USS Enterprise.

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