Austro-Hungarian crown prince Archduke Franz Ferdinand and his wife Sophia Hohenberg Chotek were assassinated in Sarajevo.
Austria-Hungary issues an ultimatum to the Kingdom of Serbia.
Beginning of mobilization in Austria-Hungary for men fit for army duty between 21 and 42 years old.
Austria-Hungary declared war on Serbia. World War began.
Germany occupied Luxemburg and continued its advance across Belgium towards France.
On the Eastern Front Russian troops were defeated near Tannenberg.
The Battle of Marna forced the Germans to retreat. Verdun became one of the main points of the Western Front.
21st to 24th December
The trial in which 32 members of the Renewal (Preporod) society accused of high treason were given various sentences.