• 6/28/1914

    Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, and his wife, Sophie, Duchess of Hohenberg, were assassinated on 28 June 1914 by Bosnian Serb student Gavrilo
  • 7/28/1914

    On July 28, 1914, one month to the day after Archduke Franz Ferdinand of Austria and his wife were killed by a Serbian nationalist in Sarajevo, Austria-Hungary declares war on Serbia, effectively beginning the First World War
  • 8/4/1914

    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. With Great Britain formally at war, the Dominions of Australia, Canada, and New Zealand entered World War I.
  • 5/7/1915

    On the afternoon of May 7, 1915, 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.
  • 11/7/1915

    Battle of Krivolak — Bulgarian forces repelled attacking French forces south of Kosturino. Battle of Banjo — The British captured the German mountain fort near Banjo, Kamerun with a loss of 50 casualties.
  • 1/19/1917

    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.
  • 4/6/1917

    On April 6, 1917, the United States formally declared war against Germany and entered the conflict in Europe. ... For three years, President Woodrow Wilson strove to maintain American neutrality. Anti-war sentiment ran across the political spectrum
  • 6/25/1917

    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.
  • 11/11/1918

    The Allied powers signed a ceasefire agreement with Germany at Compiégne, France, at 11:00 a.m. on November 11, 1918, bringing the war now known as World War I to a close. ... Between the world wars, November 11 was commemorated as Armistice Day in the United States, Great Britain, and France
  • 6/28/1919

    Five years later, on June 28, 1919, Germany and the Allies signed the Treaty of Versailles, formally ending World War I and providing for the creation of the League of Nations.