Great War

Assasination of Franz Ferdinad

Jun 28, 1914

Garbrielle Princip assasined Franz Ferdinad

Austria- Hungary

Jul 28, 1914

Austria- Hungary decided after the assasination that declaring war on Serbia was the correct decision.

Serbia

Jul 28, 1914

Austria-Hungary declared war on Serbia, causing them to have to join war.

Russia

Aug 1, 1914

Russia declares war on Germany, having Serbia's back

Germany

Aug 1, 1914

Germany declares war against Russia after Russia did not stop mobilizing against Austria- Hungary

Belgium

Aug 3, 1914

Belgium joined war when German troops invaded Belgium

France

Aug 3, 1914

France declares war on Germany hours after Germany declares war on France

Great Britain

Aug 4, 1914

Britain declared war when Germany attacked France through Belgium.

Italy

Apr 26, 1915

After signing the Treaty of London, Italy declares war on Austria- Hungary

Bulgaria

Oct 11, 1915

Bulgaria allied with Central Powers for economic reasons, causing them to join World War 1

Portugal

Mar 1, 1916

Declares war on Germany due to Uboat warfare, blocking Portugal to trade

Romania

Aug 27, 1916

Romania signs a treaty with the allies, leading them to join war due to being upset with Austria- Hungary on territory issues

Greece

Jul 2, 1917

Greece declares war on Central Powers, joining forces with the allies