Archduke Franz Ferdinand of Austria and his wife, Sophie, were assassinated on June 28, 1914 by a Serbian nationalist Gavrilo Princip.
Battle Of The Somme
On July 28, 1914, Austria-Hungary declared war on Serbia. The Austrian government blamed the Serbians for the assassination of the Archduke and his wife.
United States Declares War
On August 1, 1914, Germany declared war on Russia. Just two days later, Germany declared war on France. German troops poured into Belgium as directed under the Schleiffen Plan.
Treaty of Brest-Litovsk
The Battle of the Somme lasted from July 1, 1916 until November 1916, which was fought by the British and French against the Germans. The nearly 20,000 killed in action on July 1st, marks the single bloodiest day in the history of the British army. This devastating battle epitomized the futility of trench warfare.
On April 6, 1917, the United States declared war on Germany in response to the sinking of US ships by German U-boats. President Woodrow Wilson used unrestricted submarine warfare and the Zimmermann Telegram as justification for abandoning neutrality.
After months of delays, the Soviet government signed the peace treaty on March 3, 1918 at German-controlled Brest-Litovsk. The treaty was between the Bolshevik government of Russia and the Central Powers, thus ending Russia's participation in World War I.