The Balkan states of Bosnia and Herzegovina, had been annexed from Turkey and taken into the Austro-Hungarian Empire. This was strongly resented by many Serbs and Croats and a nationalist group, The Black Hand, was formed.
Germany declares war on Russia
Germany declares war on France.
Austria-Hungary declares war on Russia and Serbia declares war on Germany.
U.S. President Woodrow Wilson announces the U.S. will remain neutral.
The Battle of Tannenberg begins.
The First Battle of the Marnebegins. Trench warfare begins as soldiers on both sides dig in.
Battle of Ypres begins.
December 24 The unofficial Christmas truce is declared.
Germany declares a "war zone" around Great Britain, essentially effecting a submarine blockade where even neutral merchant vessels were to be potential targets.
The Dardanelles Campaign begins.
The British ocean liner RMS Lusitania is sunk by German U-boat, U-20.
22 Apr 1915The Second Battle of Ypres begins. It is during this battle that the Germans first use poison gas.
The Battle of Gallipoli begins.
21 Feb 1916 The Battle of Verdun begins. The Battle of Verdun was the longest battle of World War I and was one of the bloodiest.
31 May 1916 The Battle of Jutland, the major naval battle of the war, begins.
The Battle of the Somme begins. During the Battle of the Somme, tanks are first introduced into battle.
Germany sends the secret Zimmerman Telegram. Telegram is sent to Mexico in an effort to entice Mexico to join the war. The British intercept and decipher the coded message.
Russian Tsar Nicholas II abdicates.
The United States declares war on Germany. The first turning point.
The Battle of Passchendaele begins. (Also known as the Third Battle of Ypres)
The armistice agreed upon between the new Russian government and the Central Powers goes into effect.
Russia signs the Treaty of Brest Litovsk. It is a peace treaty between Russia and the Central Powers.
Germany launches the Spring Offensive.
German flying ace, Baron Manfred von Richthofen is shot down. More commonly known as the Red Baron.