The Z gram intercept: greatest cryptography coup of World War I

Spokesman Magazine, July, 2004 by Dennis Casey

At the outset of the war, the Germans had five transatlantic cables that ran through the English Channel. One went to Brest in France, another to Vigo in Spain, one to Tenerife in North Africa and two to New York via the Azores. The English cable ship Telconia cut them all in England's first offensive action in the war. This left a cable that ran between West Africa and Brazil that was largely American-owned that the Germans could use. In short order the allies ended that source of direct cable communications with the overseas world. Consequently, Germany was forced to use their powerful wireless station at Nauen, just a few miles outside Berlin. From this moment, German messages were routinely picked from the air and began pouring into the offices of British Naval Intelligence. In order to capture this flood of information, four new allied listening stations were established along the English coast with direct wires to Admiral Hall's offices. The positive result from this investment could not be overemphasized.

When Arthur Zimmermann dispatched his now infamous coded telegram, he elected to do so over three different routes. The message was transmitted from the German wireless station at Nauen and also over a cable controlled by the Swedish government. The Germans had agreed they would send their diplomatic traffic to the United States and elsewhere over this transatlantic cable. They also had the message typed out by an American embassy clerk and sent across the Atlantic over the U.S. State Department cable as instructed by Colonel House. Admiral Hall's operatives intercepted all three messages.

When the German government made the decision to employ unrestricted submarine warfare, President Wilson, who had struggled to attain a peace in Europe without victory and who had worked extensively with the British and the German governments, now felt his policies and many attempts to peace had led to nothing. Still committed to maintaining America's neutrality, President Wilson clung to the idea of not getting involved in the war in Europe, even against the advice of Robert Lansing, his Secretary of State.

When Wilson finally learned of the Zimmermann telegram and that British Intelligence had intercepted it in Mexico, Admiral Hall did not want President Wilson to know that the British were intercepting American cables as well; the last stone had been cast. President Wilson directed Secretary Lansing to release the telegram to the press. On Thursday, March 1, 1917, the text of Zimmermann's telegram appeared in the Times and the World, both New York newspapers.

The reaction across the United States to the publication of the Zimmermann telegram according to Secretary Lansing was profound. When Arthur Zimmermann publicly admitted to having sent the telegram, America seemed to sit up and gasp. Newspapers across the country took the telegram to be a direct threat to the United States. The Detroit Times expressed it perhaps best when an editor's comment said," It looks like war for this country. All these papers had been ardently neutral until Zimmermann shot an arrow in the air and brought down neutrality like a dead duck." On April 2, President Wilson asked Congress for a declaration of war. For Zimmermann the entire effort involving the telegram had been a minor plot. For Americans, the entire affair killed the illusion that the United States could go about its business separate from other nations. For most Americans it was the end of innocence.