Austria declared war on Serbia
Germany declared war on Russia
Germany declared war on France
British declaration of war
Battle of Tannenberg
Japan declared war on Germany
Russia declared war on Turkey
Britain and France declared war on Turkey
Germany becomes the 1st nation to use poison gas in warfare, at the second battle of Ypres.
Tanks are used in battle for the first time, at the battle of Somme
The U.S. Congress declares war on Germany
U.S. Troops join the fighting in Europe
World leaders sign the Treaty of Versailles. U.S. Senate rejects it.
