About National Day of Unity
National Unity was established by the Italian Parliament the day 17th of March 1861 by Royal Decree.
Before 1861, the peninsula was fragmented, split into rival states and regions which had changed hands, allegiances, and boundaries frequently over the centuries. They included the Grand Duchy of Tuscany, the Duchy of Modena, the Papal States, Kingdom of Sardinia, Kingdom of Lombardy-Venetia, and Kingdom of the two Sicilies.
Generally, Italy opts to mark the founding of the Republic on June 2nd, rather than the unification itself. On June 2nd 1946, Italians narrowly voted (54:45) in a constitutional referendum to abolish the monarchy.