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WWI begins
• June 28 – Assassination of Archduke Franz Ferdinand of Austria.
• July 28 – Austria-Hungary declares war on Serbia, starting WWI.
• August 1-4 – Germany declares war on Russia and France; Britain declares war on Germany.
• September 6-10 – First Battle of the Marne halts German advance into France. -
Stalemate & Trench Warfare
• April 22 – Germany uses poison gas for the first time (Second Battle of Ypres).
• May 7 – Sinking of the Lusitania by a German U-boat, killing civilians, including Americans.
• October – Bulgaria joins the Central Powers; Serbia is invaded. -
Major Battles
• February-December – Battle of Verdun (longest battle of the war).
• July-November – Battle of the Somme; first use of tanks by the British. -
Turning Points
• March – Russian Revolution begins; Tsar Nicholas II abdicates.
• April 6 – The U.S. declares war on Germany.
• November – Bolsheviks seize power in Russia; Russia begins withdrawing from the war. -
War Ends
• March – Germany launches its Spring Offensive but fails.
• July-August – Allied forces counterattack in the Second Battle of the Marne.
• November 11 – Germany signs the Armistice; war officially ends. -
Aftermath
• June 28 – Treaty of Versailles is signed, imposing heavy penalties on Germany.