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.
Spanish conquest of Sardinia
The Spanish conquest of Sardinia, also known as the Spanish expedition to Sardinia, took place between the months of August and November 1717. It was the first military action between the Kingdom of Spain and the Holy Roman Empire after the War of the Spanish Succession (1701–1714), and was the direct cause of the War of the Quadruple Alliance (1718–1720). The Spanish troops commanded by the Marquis of Lede and Don José Carrillo de Albornoz, 1st Duke of Montemar, supported by the Spanish fleet, defeated the Emperor's troops easily, and conquered the entire island of Sardinia, which had been ruled by the Emperor since the Treaty of Rastatt (1714), returning it again and for the final time to Spain.