World War I Timeline
June 28 - Archduke Franz Ferdinand, prince to the Austria-Hungary throne, is assassinated in Sarajevo by a Serbian named Gavrilo Princip.
July 23 - Austria-Hungary makes demands on Serbia for retribution. Serbia does not meet demands.
July 28 - Austria-Hungary declares war on Serbia. Russia begins mobilizing its troops. August 1 - Germany declares war on Russia.
August 3 - Germany declares war on France as part of the Schlieffen Plan. August 4 - Germany invades Belgium. Britain declares war on Germany. August 23 to 30 - The Battle of Tannenberg is fought between Germany and Russia. The Germans defeat the Russian Second Army.
September 5 to 12 - The advancing German army is stopped before Paris by the British and French at the First Battle of the Marne. The Germans dig in and four years of trench warfare begins.
October 19 to November 22 - The Allies defeat the Germans at the First Battle of Ypres. November 2 - The British begin a naval blockade of Germany. November 11 - The Ottoman Empire declares war on the Allies.
December 24 - An unofficial truce is declared between the two sides at Christmas.