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.
Northern Italy
After the French Revolution in the late 18th century Northern Italy was conquered by the French armies, many client republics were created by Napoleon and in 1805 a new Kingdom of Italy, made of all of Northern Italy but Piedmont that was annexed to France, was established with Milan as capital and Napoleon as head of state.
In the congress of Vienna, the Kingdom of Sardinia was restored, and furthermore enlarged by annexing the Republic of Genoa to strengthen it as a barrier against France. The rest of Northern Italy was under Austrian rule, either direct like in the Lombardo-Venetian Kingdom or indirect like in the Duchies of Parma and Modena. Bologna and Romagna were given to the Papal State.
The Austrian imperial government was unpopular because of their anti-liberal politics and Northern Italy became the intellectual centre leading the Italian unification process. Piedmont and the Kingdom of Sardinia, in particular, was the state that launched Italy's unification in 1859–1861. After defeating the Austrians in 1859 and annexing Northern Italy the new state proceeded to launch a campaign to conquer Southern and Central Italy and Turin briefly became the capital of the whole of Italy.