The assassination of Archduke Franz Ferdinand by Gavrilo Princip in 1914 had a direct effect on the outbreak of war, while the Treaty of Versailles was signed on exactly the same date five years later in 1919.

On the 23rd July 1914, Austria-Hungary issued an ultimatum to Serbia specifically designed to be rejected and lead to war between the two countries.

The National Assembly of Romanians of Transylvania and Hungary declared the unification of Transylvania and the Kingdom of Romania.