March 1, 1917 - The Zimmerman Telegram

94 years ago today, the headline below was dropped like a bomb on the front page of the New York Times. Its news that Germany had proposed an alliance with Japan and Mexico against the US finally nudged a waffling Woodrow Wilson over the edge, leading to a declaration of war against Germany and her allies.

The telegram in code below is the fatal VERSION of the telegram that was presented by Britain to the United States. But there's much more interesting history behind the story...

You see, that's not the version of the telegram that Britain's cryptanalysts in Room 40 initially intercepted and decoded. On January 16,1917, German Foreign Minister Arthur Zimmerman transmitted the original version from Berlin to Germany's embassy in the US. However, the telegram didn't go straight to the US. You see, on the first day of WW I, the British ship Telconia cut German's transatlantic cables, a farsighted move that forced Germany to communicate via other nations' cables or via radio...both options rendering them much more vulnerable to interception.

So Zimmerman sent that fateful telegram by way of Sweden to the US, using a US code (more Wooodrow Wilson brilliance). And when Britain intercepted and decrypted it, they had to step carefully and not raise questions of how they were intercepting neutral Sweden's cables or decrypting American cyphers.

What they did is arrange to have an operative in Mexico intercept the version that was sent there and have it decyphered again. Then they sat on that telegram until it became clear that only a serious nudge would bring the US into World War I. In the end, they revealed the SECOND version of the Zimmerman telegram to the US, leading us to make war against Germany after an infuriated American public demanded it.

The facts in this story are one of many fascinating anecdotes from history found in David Kahn's fantastic book, "The Codebreakers".