One of the most important examples of code breaking was the British decryption of the Zimmermann Telegran, a factor in bringing America into the War. Britain controlled the trans-Atlantic cable links to America. The Germans used the cables to send telegram messages to their diplomatic missions in America. The Germans encoded sensative messages, assuming the British could not read them. German Foreign Minister Arthur Zimmermann sent a coded message to the German Ambassador in Mexico von Eckhardt (January 16, 1917). It instructed him to inform the Mexican Government that Germany would soon resume unrestricted submarine warfare which in a few months would knock Britain out of the War. The Germans assumed this would cause America to declare war. Zimmermann offered Mexico U.S. territory if Mexico would join Germany in the war. We are unsure about the German decession-making process. Surely the failed Mexican expedition must have been a factor. The telegram read, "We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal or alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico, and Arizona. The settlement in detail is left to you. You will inform the President of the above most secretly as soon as the outbreak of war with the United States of America is certain and add the suggestion that he should, on his own initiative, invite Japan to immediate adherence and at the same time mediate between Japan and ourselves. Please call the President's attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace." Signed, ZIMMERMANN." It was possible the most blatantly incompetent diplomatic approach in history. We are not sure to what extent the Kaiser was involved, but Zimmermann would not have made this offer without the Kaiser's approval. British Naval Intelligence cryptographers using a captured German codebook decoded the message. were surprised when a encoded German transmission came across their desks. German actions in the War, especially in Belgium and on the highseas had brought most Americans over to the Allied side, although public opinion still opposed entry in the war. The British turned the telegram over to the American Embassy in London (February 24, 1917). The Wilson Administration released the telegram to the press (March 1). Some at first thought the telegram a forgery which the Germans and Mexicans first claimed. Zimmermann inexplicteldly admitted he had sent the message (March 3). The American public was outraged. Public opinion shifted toward a declaration of war. [Tuchman] Despite substantial pascifist sentiment, there waslittle opposition to entering the War.
President Wilson decided to support Carranza in the Mexican Civil War (1915). This enfuriated northern commander Panco Villa who had expected American assistance. Villa retaliated by ordering attacks ion americans in northern Mexico and along the border. The most serious incident occurred when Villa's men stopped a Mexican train and found several American engineers (January 1916). The Villistas forced the Americans off the train and then stripped, shot, md mutilated them. Villa ordered his men to stay south of the border to avoid an incident on American terriory which he seems to have realized would have serious consequences. The exception to this was an attck on the border town of Columbus, New Mexico (March 9, 1916). This was no accident. A substantial Villista force attacked the town and its small military post. They shot and killed several resident and burned down much of the town. There were 24 casualties. They escaped back into Mexico with horses and mules, merchandise and guns from the stores, as well as money. Americans were outraged and newspapers throughout the country demanded action. Wilson was also outraged seeing Villa as little more than a bandit. President Wilson ordered General John J. Pershing to enter Mexico and arrest Villa. Pershing was an old calvalry man who had commanded black troops (the Buffalo soldiers) on the Western frontier, earning him the nick name Black Jack Pershing. Perhing crossed the border with a 12,000 mn expeditionary force. Eventually almost the entire American Army was involved in the operation. Villa seems to have anticipated the American reaction and used the time after the Columbus raid to disperse and conceal his forces. Pershing entered Mexico in two columns looking for Villa. The whole affair is generally seen as a minor footnote to the massive World War I drama in Europe. It is not well established, however, just how the affair affected German thinking.
Britain controlled the trans-Atlantic cable links to America. Germany had no access to these cables and at the time radio communication over that distance was not possible. The British cut the German cables in the Atlantic and shut down German wireless stations in neutral countries. Thus to commuicate with its diplomatic posts in the Western Hemisphere, the Germans had to send messages through the British controlled cables to communicated with their diplomatic posts in the Western Hemishere.
The Germans believed that they could safely do this for two reasons. First they encoded the message. Second, President Wilson had granted the German diplomats the use of American diplomatic traffic. He did this at the time when he was still hopeful of negotiating an end to the War and wanted to remain in touch with the German Foreign Ministry. (That the Germans would taken advantage of this to negotiate an attack on the United States seems the height of diplomatic betrayal.) The German Foreign Ministry believed that the British would refrain from intercepting or at least admitting that they had intercepted American diplomatic messages because it woukd cause a diplomatic incident with the United States.
Arthur Zimmermann may be the worst foreign minister in German history, although NAZI Foreign Minister Joachim von Ribbentrop would be a close comntender. Zimmwermann is best known for the disastrous Zimmermamm Telegram which helped bring America into World war I. Zimmermann received his doctorate of law. He pursued a diplomatic career (1893). He served in Canton. He was in China during the Boxer Rebellion. Foreign Secretary Gottlieb von Jagow resigned in protest as the German Government began to move toward unrestricted submrine warfare. Von Jagow realized it would inevitably bring America into the War. Kaiser Wilhelm II appointed Zimmermann who was Von Jagow's deputy as the new foreign secretary (November 1916). His appointed came as a result of strong contacts with the military. Zimmermann strongly supported the Third Supreme Command, essentially the military dictatorship led by Paul von Hindenburg and Erich Ludendorff. Zimmermann strongly supported the military high command's desire to reimpose unrestricted submarine warfare as a way of finally achieving victory, even though it might bring America into the War. Zimmermann like many Europeans at the time was not concinced that America with its polygot population was a real nation capable of projecting power. Zimmermann answer to that was to negotiate an alliance with Mexico, Risking war with America to be offset by an alliance with Mexico can only be seen as diplomatic lunacy. While he is best known for the infamous Telegram, he had his hand in other momentius events. He supported an Irish rebellion, an Indian rebellion, and to help the Communists undermine Tsarist Russia. It was Zimmermann who helped arrange to get Lennin from Switzerland and send him across Germany in a sealed train toward the fampus Finland Station. Zimmermann having done emense damage, resigned (August 1917). By that time, American doughboys were streaming into French ports and the Bolshevivks were posed to seized power in Russia. The American infantry would prove decisive in the 100 Days Campaign that broke the German Western Front wide open (September-November 1918). Zimmermann died in 1940.
The Zimmermann Telegram was transmitted by radio and also across two telegraph routes under the cover of diplomatic messages by two neutral governments, Sweden and the United States. The U.S. Embassy in Berlin as the German cables were cut had to communicate through the good offices of two neutral countries (the United States and Sweden). Direct telegraph transmission once the War began was no longer possible because the British had severed the German trans-Atlantic cables. So the Germans used what became known as the 'Swedish roundabout'. The cables passed through a relay station at Porthcurno, near Land's End in Cornwall, the westernmost tip of England. Here the signals had to be boosted for the long trans-oceanic transmission. The cable traffic through the British Porthcurno relay was secretly copied to British intelligence. Which mean the codebreakers and analysts at the Admiralty famed Room 40. There is considerable confussion about this as the British did not want it to appear that they were reading American Diplomaic commuications. Thus inaccuate cover stories were planted that persist in some historical accounts.
In the case of the Zimmermann telegram, the Swedish roundabout was not used. The Germans appealed to the United States for assistabce with their diplomatic communications. President Wilson as an act of good faith permitted the Germans a limited use of its diplomatic cables so that they could communicate with their ambassador in Washington. The British knew about this because they were secretly listening in as the cables transitted Britain. The President Wilson approved this with the idea that the cables would be used to further his peace proposals. [Gannon] The idea that the Germans would use this facility meant to promote peace to enduce Mexico to attack the United defies comprehension forboth moral and practical reasons.
The German Foreign Ministry delivered the cable to the U.S. Embassy in Berlin and then transmitted by diplomatic cable to Copenhagen and then on to London to be sent over trans-Atlantic cable to the German Embassy in Washington. It was handek\led by U.S. operators.
The United States required that all messages using this facility be sent in the clear. The Germans believed that the U.S. cable was secure and used it extensively. It of course was not secure. The British were listening in. The Germans of course could not send the Zimmermanntelegram in the clear. The Germans managed to persuade Ambassador James W. Gerard to send this message in a coded form. It was transmitted (January 16, 1917). [West, pp. 83, 8792.] Unbenongst to the Germans, it woud seal the fate of the German Empire.
Once it arrived at the German Embassy in Washington, the Embassy staff sent it on to German Ambassador von Eckardt in Mexico City by commercial telegraph. Well before this had occurred, British intelligence to intercept it and delivered it to Room 40.
German Foreign Minister Arthur Zimmermann sent a coded message to the German Ambassador in Mexico von Eckhardt (January 16, 1917). It instructed him to inform the Mexican Government that Germany would soon resume unrestricted submarine warfare which in a few months would knock Britain out of the War. The Germans assumed this would cause America to declare war. Zimmermann offered Mexico U.S. territory if Mexico would join Germany in the war. We are unsure about the German decession-making process. Surely the failed Mexican expedition must have been a factor. The telegram read, "We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal or alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico, and Arizona. The settlement in detail is left to you. You will inform the President of the above most secretly as soon as the outbreak of war with the United States of America is certain and add the suggestion that he should, on his own initiative, invite Japan to immediate adherence and at the same time mediate between Japan and ourselves. Please call the President's attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace." Signed, ZIMMERMANN."
It was possible the most blatantly incompetent diplomatic approach in history. We are not sure to what extent the Kaiser was involved, but Zimmerman would not have made this offer without the Kaiser's approval. America of course had never before sent an army to Europe. The Germans seemed unaware of the potential impact of American intervention. They were aware that America did not have an army that could be immediately dispatched. And the Germany Navy had informed the government that their U-boats would prevent an Anerican Army from reaching France. Military men might be excused for not understanding foreign affairs, but not diplomats. But Zimmermann was from the beginning the military's man in the Foreign Ministry.
The major combatant countries set up extensive cryptological organizations. The best-known cryptological coup of World War I was surely the Zimmermann Telegram incident. Two army cryptanyalysis' recognized that the message was encoded in a German diplomatic code that they called '0075'. Their unit had been working on this code for months with the assistance of a captured German code book. British Naval Intelligence cryptographers were surprised when an encoded German transmission came across their desks. The cable was a long one, and consisted of about a thousand numerical code groups. They suceeded in cracking the the code when they realized that 0075 was one of a series of two-part codes that the German Foreign Office had based on two zeros and two digits. The digits always showed a numerical difference of 2. Naval intelligence was able to crack this code and subsequently many other German codes. The code breakers were stunded to learn not only who sent it, but the incendiary contents.
The British had a problem. The contents of the cable was incendiary. The Foreign Office knew this and that it could hedlp achieve a long time goal, brining America into the war. But they had two problems. First, they did not want to admit that they were monitoring american diolomatic messages. That could cause an international incident at just the time they wanted America to be a new ally. Second, they did not want to alert the Germans that they had broken their diplomatic code. The British sollution was a masterpiece of diplomacy.
First they managed to get a copy of the telegram (in ciphertext) from the telegraph office in Mexico City. The British assumed that the German Embassy in Washington would use commercial telegraph to forward the cable to their Embassy in Mexici City. It woukd have been the fasted way at the time. This meant that the MNexico City telegraph office woukd have a copy. A "Mr. H.", a British agent in Mexico thus bribed an employee at the telegraph company to get a copy.
Sir Thomas Hohler was the British ambassador in Mexico and after the War in his autobiography revealed that he was Mr. H. This copy could be given the Americans without diplomatic embarrassment. The German Embassy in Washington had sent the message using using cipher 13040. The British had captured a copy of this code book in Mesopotamia where they were fighting the Ottomans, amember of the Central Powers. (Ottoman units had German military adviswrs.)
The British solved their second concern by planting the story that a deciphered copy of the cable had been stolen in Mexico Bity. The German government was outraged and furiously ordered their Embassy in Mexico City to track down the traitor who sold the canle to the British.
German actions in the War, especially in Belgium and on the highseas had brought most Americans over to the Allied side. First the invasion of neitral Belgium and stories of attrocities (embelished but not entirely fabricated by British propaganda) had an impact. Then there was the sinking of the Lusitania. This had powerfully affected public opinion and almost brought America into the War until the Germans agreed to restrictions on their U-boat campaign. Public opinion, however, while decidedly pro-Allied, was still strongly opposed to entring the war. Staying out of the War had been a major factor in President Wilson's reelection (1916). Only a collosal blunder by the Germans could have brought America into the War.
The British informed the U.S. Embassy in London about the telegram (February 19, 1917). "Blinker" Hall, the head ofvthe Naval intelligence unit (Room 40), showed the Telegram to the secretary of the U.S. Embassy in Britain, Edward Bell. Bell was at first could not believe it and thought that it was a forgery, he then then became enraged absorbing what the Germans were doing. The next day, Hall sent a copy to U.S. Ambassador Walter Page (February 20). Then Ambassador Page met with Foreign Minister Balfour (February 23). He ws given the ciphertext, the message in German, and the English translation. Page immediately reported the story to President Woodrow Wilson, including details so that the cable could be authenticated from the telegraph company files in Washington. The British could be doubted, although the fact that Balfour himself was involved meant that the British Government stood behinf the account. In Washingtin it was confirmed that the German Embassy forwarded tghe message to their embass\y in Mexio City. The shocked Wilson Administration after authenticating it, quickly released the telegram to the American press (March 1). Some at first thought the telegram a forgery which the Germans and Mexicans quickly claimed. (It is possible the British has sent a fake telegram, but the German Embassy in Washingtom retransmitting it to Mexico City could not be explained away.) The United States had broken off diplomatic relations wuth Germany, but was still at peace. It seemed unbelievable that Germany would so blantantly move against the United States. Foreign Minister Zimmerman, however, inexplicteldly ended the speculation. In a rambling speech attempting to justify himself, he essentially admitted he had sent the message (March 3). He put the blame on America for the breach in relations. He was convinced that Germany was posed to win the War and America was being unreasonable. He explained We have 500,000 reservists in America who would rise in arms against your government. The American public was outraged. It confirmed the image that many in America had of Germany as a reckless, outlaw nation. Public opinion shifted toward a declaration of war. [Tuchman] Despite substantial pascifist sentiment, there was now little opposition to entering the War.
Gannon, Paul. Inside Room 40: The Codebreakers of World War I (London, Ian Allen Publishing, 2011).
West, Nigel. The Sigint Secrets: The Signals Intelligence War, 1990 to Today-Including the Persecution of Gordon Welchman (New York: Quill, 1990).
Tuchman, Barbara. The Zimmermann Telegram.
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