-
Archduke Franz Ferdinand was assassinated in Sarajevo
-
Russia moves its army to interfere with Austria-Hungary, to defend its ally, Serbia. This creates a chain reaction, causing the rest of the European Powers to interfere too.
-
Germany invades Belgium, sparking the beginning of World War I.
-
A German sub sinks passenger liner Lusitania. Killing 1,198 people. 128 were Americans.
-
A telegram sent from Arthur Zimmerman to Mexico was intercepted by the British. The telegram promised that if Mexico back their lost land. Due to this interception, America put out a public opinion to join the war.
-
Congress declares war on Germany. The United States enters on the side of France and Britain.