The Lateran Treaty is ratified, bringing Vatican City into existence.

The Lateran Treaty (Italian: Patti Lateranensi; Latin: Pacta Lateranensia) was one component of the Lateran Pacts of 1929, agreements between the Kingdom of Italy under King Victor Emanuel III and the Holy See under Pope Pius XI to settle the long-standing Roman Question. The treaty and associated pacts were named after the Lateran Palace where they were signed on 11 February 1929, and the Italian parliament ratified them on 7 June 1929. The treaty recognized Vatican City as an independent state under the sovereignty of the Holy See. The Italian government also agreed to give the Roman Catholic Church financial compensation for the loss of the Papal States. In 1948, the Lateran Treaty was recognized in the Constitution of Italy as regulating the relations between the state and the Catholic Church.