February 2, 1848

The Treaty of Guadalupe Hidalgo Is Signed

About a third of what was once Mexico becomes part of the United States. Sixty-nine years later, Germany would use this fact to try to entice Mexico to invade the U.S. and win it back.

June 28, 1914

Archduke Franz Ferdinand Is Assassinated

Tensions in Europe were so high that virtually any leader's untimely death could have started a war. Franz was just the lucky winner, or loser, depending on how you look at it.

July 28-August 6, 1914

European Nations Declare War on Each Other

A tangled network of alliances meant that nearly every European nation was obligated to go to war with someone. So they all did, even though they didn't really have a very good reason for the whole thing.

May 7, 1915

A German U-Boat Sinks the Lusitania

The ship was supposedly non-military and the passengers included Americans, but there was a good deal of British military contraband aboard, as well as gun mounts hidden beneath the deck in case the boat needed to be commissioned for service in a war with Germany. The U.S. protested loudly against the sinking of a passenger ship, and Germany promised to never do it again. Like, ever.

November 7, 1916

Woodrow Wilson Re-elected U.S. President

His campaign slogan was, "He Kept Us Out of the War," which would be true for another five months before he would cave in and take America into its very first overseas war.

January 16, 1917

The Zimmermann Telegram is Sent

The telegram was discovered and translated by the British three days later, but then it took nearly a month for people to believe it was real. When will people stop using the telegram machine for practical jokes?

February 1, 1917

Germany Begins Unrestricted Submarine Warfare (Again)

They'd been sinking whatever ships they wanted to for a while (Lusitania anyone?), but now they were more transparent about their policy of killing innocent people.

March 1, 1917

The Zimmermann Telegram is Publicized in the U.S.

Skeptics persisted until Zimmermann admitted to writing it several days later. The American public was understandably outraged. Mexico and Japan quickly made it clear they had no intention of invading.

April 6, 1917

The U.S. Declares War On Germany

Wilson had finally had enough of Germany thinking it could do whatever it wanted in the Atlantic, beat up on everyone in Europe, and think up dastardly plots via telegrams. It was time for action.

November 11, 1918

An Armistice Is Signed Ending the War

Germany and Austria-Hungary were defeated before this, but everybody waited until 11:11AM on November 11 to actually stop fighting because it sounded cooler that way. Too bad it wasn't 1911.

June 28, 1919

The Treaty of Versailles Is Signed

The U.S. got lots of respect from everybody, but France and England were petty jerks and ended up ultimately causing World War II by making Germany agree to accept blame for the whole war, disarming them, and making them pay a ridiculous amount of money in war reparations. A guy named Adolf Hitler managed to rise to power based in part on lasting German resentment about the deal.