Curated timeline

World War I

The Great War that shattered empires. From the assassination in Sarajevo to the trenches of the Western Front and the Treaty of Versailles.

• Assassination of Archduke Franz Ferdinand (June 28, 1914)

  Gavrilo Princip assassinates the Austro-Hungarian heir in Sarajevo, sparking the July Crisis.

• Austria-Hungary Declares War on Serbia (July 28, 1914)

  Austria-Hungary declares war on Serbia, initiating hostilities after the assassination.

• Germany Declares War on Russia (August 1, 1914)

  Germany declares war on Russia, escalating the conflict into a European war.

• Germany Invades Belgium (August 4, 1914)

  Germany invades neutral Belgium, prompting Britain to declare war.

• Battle of Tannenberg (August 26-30, 1914)

  Germany decisively defeats Russia on the Eastern Front, destroying the Russian Second Army.

• First Battle of the Marne (September 6-12, 1914)

  Allies halt Germany's advance near Paris, preventing quick German victory.

• First Battle of Ypres (October 19-November 22, 1914)

  Allies prevent Germany from capturing Channel ports, establishing trench warfare.

• Ottoman Empire Enters the War (October 29, 1914)

  Ottoman Empire joins Central Powers, opening Middle Eastern front.

• Christmas Truce (December 24-25, 1914)

  Informal ceasefires see soldiers fraternize across no man's land on the Western Front.

• Armenian Genocide Begins (April 24, 1915)

  Ottoman authorities begin systematic deportations and mass killings of Armenians.

• Gallipoli Campaign Begins (April 25, 1915)

  Allied landings on Gallipoli Peninsula attempt to secure passage to Russia.

• Second Battle of Ypres (April 22-May 25, 1915)

  Germany uses poison gas for the first time on the Western Front.

• Sinking of the Lusitania (May 7, 1915)

  German U-boat sinks British liner, killing 1,198 civilians, escalating U.S. tensions.

• Italy Declares War on Austria-Hungary (May 23, 1915)

  Italy joins the Allies, opening the Italian front against Austria-Hungary.

• Battle of Verdun (February 21-December 18, 1916)

  Germany's attempt to 'bleed France white' becomes longest single battle of WWI.

• Battle of Jutland (May 31-June 1, 1916)

  Largest naval battle of WWI maintains British naval supremacy despite losses.

• Brusilov Offensive (June 4-September 20, 1916)

  Russia's most successful offensive severely weakens Austria-Hungary.

• Battle of the Somme (July 1-November 18, 1916)

  British offensive suffers 60,000 casualties on first day in bloodiest battle of WWI.

• Romania Enters the War (August 27, 1916)

  Romania joins Allies but is quickly defeated by Central Powers coalition.

• First Use of Tanks (September 15, 1916)

  British deploy first tanks at Flers-Courcelette, introducing new warfare technology.

• Zimmermann Telegram (January 16, 1917)

  German proposal for Mexico-Germany alliance intercepted by British intelligence.

• Germany Resumes Unrestricted Submarine Warfare (February 1, 1917)

  Germany resumes unrestricted U-boat attacks, escalating tensions with neutral nations.

• February Revolution (March 8-16, 1917)

  Russian Revolution overthrows Tsar Nicholas II, establishing Provisional Government.

• United States Declares War on Germany (April 6, 1917)

  U.S. enters war due to submarine warfare and Zimmermann Telegram revelations.

• Nivelle Offensive (April 16-May 9, 1917)

  Failed French offensive leads to widespread mutinies in the French army.

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