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Archduke Franz Ferdinand of Austria
Austro-Hungarian throne and his wife Sophie, Duchess of Hohenberg were assassinated in Sarajevo on 28 June 1914. They were shot to death by Gavrilo Princip, a Bosnian student and member of the Serbian secret society "Black Hand". -
Austria-Hungary
Austria-Hungary declares war on Serbia, effectively beginning the First World War. -
Great Britain
Great Britain declared war on Germany at 11:00 p.m. for violating Belgian neutrality. The United States declared neutrality at the outbreak of World War I. the Dominions of Australia, Canada, and New Zealand entered World War I. -
German submarine
The British ocean liner Lusitania is torpedoed without warning by a German submarine off the south coast of Ireland. Within 20 minutes, the vessel sank into the Celtic Sea. Of 1,959 passengers and crew, 1,198 people were drowned, including 128 Americans. -
Battle of Krivolak
The French failed to capture an important Bulgarian stronghold located at a monastery in the Vardar Macedonia region. French passenger ship France IV was sunk in the Mediterranean Sea 85 nautical miles southwest of Sardinia, Italy by German submarine SM U-38, with her crew surviving. -
Alfred Zimmermann
The British intercept a telegram sent by Alfred Zimmermann in the German Foreign Office to the German embassies in Washington, D.C., and Mexico City. Its message outlines plans for an alliance between Germany and Mexico against the United States. -
War against Germany
The United States formally declared war against Germany and entered the conflict in Europe. Fighting since the summer of 1914, Britain, France, and Russia welcomed news that American troops and supplies would be directed toward the Allied war effort. -
Battle of Messines
The Nivelle Offensive in April and May had failed to achieve its more grandiose aims, had led to the demoralisation of French troops and confounded the Anglo-French strategy for 1917. -
Western Front
After more than four years of horrific fighting and the loss of millions of lives, the guns on the Western Front fell silent. Although fighting continued elsewhere, the armistice between Germany and the Allies was the first step to ending World War I. -
Peace Treaty
The Versailles Peace Treaty signed. Officially ended World War I. The German ships were to be interned at a neutral port but were instead interned at Scapa Flow, the Grand Fleet's anchorage during the war, upsetting the German Navy.