Italy, 17 March 1861 – 17 March 2020
The Kingdom of Italy was a state which existed from 17 March 1861—when King Victor Emmanuel II of Sardinia was proclaimed King of Italy—until 1946, when civil discontent led an institutional referendum to abandon the monarchy and form the modern Italian Republic. The state was founded as a result of the unification of Italy under the influence of the Kingdom of Sardinia, which can be considered its legal predecessor state.
You can find historical documents on the Kingdom of Italy on Archives Portal Europe, including an exhibition on the history of Italy from the Schweizerisches Bundesarchiv:
Pictured: the Kingdom of Italy’s flag (source: Flickr)