Kingdom of Sardinia
On 17 March 1861, law no. 4671 of the Sardinian Parliament proclaimed the Kingdom of Italy, so ratifying the annexations of all other Apennine states, plus Sicily, to the Kingdom of Sardinia. The institutions and laws of the Kingdom were quickly extended to all of Italy, abolishing the administrations of the other regions. Piedmont became the most dominant and wealthiest region in Italy and the capital of Piedmont, Turin, remained the Italian capital until 1865, when the capital was moved to Florence. But many revolts exploded throughout the peninsula, especially in southern Italy, and on the island of Sicily, because of the perceived unfair treatment of the south by the Piedmontese ruling class. The House of Savoy ruled Italy until 1946 when Italy was declared a republic by referendum. In this referendum the southern regions, including Sardinia, voted overwhelmingly in favor of the House of Savoy, with the results being 63.8% in favor of maintaining the monarchy.
Roman Italy
The crisis of the third century hit Italy particularly hard and left the eastern half of the Empire more prosperous. Nevertheless, the islands of Corsica, Sardinia, Sicily and Malta were added to Italy by Diocletian in 292 AD, and Italian cities such as Milan and Ravenna continued to serve as capitals for the West. The Bishop of Rome gained importance during Constantine's reign and was given religious primacy with the Edict of Thessalonica under Theodosius I. Italy was invaded several times by the barbarians and fell under the control of Odoacer, when Romulus Augustus was deposed in 476 AD. In the sixth century, Italy's territory was divided between the Byzantine Empire and the Germanic peoples. After that, Italy remained divided until 1861, when it was reunited in the Kingdom of Italy, which became the present-day Italian Republic in 1946.