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Archduke Assassination
Archduke Franz Ferdinand is assassinated in Sarajevo. His death is the event that sparks World War I. -
Russia Mobilizes
Russia mobilizes its army to intervene against Austria-Hungary in favor of its ally, Serbia. The move leads to the mobilization of the rest of the European Great Powers, and inevitably to the outbreak of hostilities. -
World War I Begins
Germany invades Belgium, beginning World War I. -
Germans start fire
The Germans fire shells filled with chlorine gas at Allied lines. This is the first time that large amounts of gas are used in battle, and the result is the near-collapse of the French lines. -
Lusitania Sinks
A German submarine sinks the passenger liner Lusitania. The ship carries 1,198 people, 128 of them Americans -
Germany Limits Submarines
Reacting to international outrage at the sinking of the Lusitania and other neutral passenger lines, Kaiser Wilhelm suspends unrestricted submarine warfare. -
First Tanks
The British employ the first tanks ever used in battle, at Delville Wood. -
Submarines Back
Germany resumes unrestricted submarine warfare in European waterways. -
Zimmerman Telegram
British intelligence gives Wilson the so-called Zimmermann Telegram, a message from German foreign secretary Arthur Zimmermann proposing that Mexico side with Germany in case of war between Germany and the United States. -
Wilson For War
President Wilson outlines his case for war to Congress. -
U.S. Enters War
Congress authorizes a declaration of war against Germany. The United States enters World War I on the side of France and Britain. -
selective service act
Congress passes the Selective Service Act authorizing the draft. Although criticized for destroying democracy at home while fighting for it abroad, President Wilson claims he sees no other option and signs the bill into law. -
Germany and Russia Peace
The Germans sign a peace treaty with the new Bolshevik government of Russia. The treaty give Germany land that had been the Ukraine and Poland, and peace on the Eastern Front allows Germany to shift soldiers to the Western Front, causing problems for the French, British, and Americans. -
Battle of Cantigny
The Battle of Cantigny is the first major American offensive of the war. -
Battle of St. Mihiel
The Battle of St. Mihiel begins when 300,000 American troops under the direct command of General Pershing fling themselves into the German lines. -
