Woodrow Wilson campaigned for re-election in the 1916 presidential campaign on the slogan “He kept us out of war.” He won by the thinnest of margins because of the implicit promise that he would continue to keep American out of the war that had ravage Europe for two years. The United States was neutral, isolationist, xenophobic, and happy to stay that way. (You see where this is going, right?)

Wilson had barely been sworn into office when international events made it difficult to keep that promise. In February, Germany broke its pledge to limit submarine warfare. In response, the United States broke off diplomatic relations with Germany. Anti-German sentiment began to spread.

The triggering event that brought America into the war occurred on February 24, when the British shared a little tidbit they’d been sitting on for a month. In January, British cryptographers deciphered a telegram they had intercepted from German Foreign Minister Arthur Zimmermann to Germany’s ambassador, Heinrich von Eckhardt. The telegram instructed von Eckhardt to offer Mexico land in Texas, New Mexico and Arizona (all areas that Mexico had previously lost to the United States) in exchange for alliance with Germany.

Five days later, the contents of the Zimmermann telegram appeared in the American press. Public flipped like an Olympic gymnast.

United States declared war on Germany on April 6, 1917: a latecomer in a war that made no sense.**

* I really wanted to title this post “That Time Western Union Started a War.” But sometimes a body has to show restraint.

**That’s a hundred years ago today, in case you didn’t catch it. Expect commemoration. In fact, go looking for it. Here’s a link to get you started: http://www.pritzkermilitary.org/explore/wwi/