[9][10][11] Before becoming a possession of the House of Savoy, the medieval Kingdom of Sardinia had been part of the Crown of Aragon and then of the burgeoning Spanish Empire.

With the Treaty of The Hague (1720), the island of Sardinia and its title of kingdom were ceded by the Habsburg and Bourbon claimants to the Spanish throne to the Duke of Savoy, Victor Amadeus II.

The Congress of Vienna (1814–1815), which restructured Europe after Napoleon's defeat, returned to Savoy its peninsular possessions and augmented them with Liguria, taken from the Republic of Genoa.

In 1847–1848, through an act of Union analogous to the one between Great Britain and Ireland, the various Savoyard states were unified under one legal system with their capital in Turin, and granted a constitution, the Statuto Albertino.

The Savoys themselves referred to their possessions as a whole as "the States of the King of Sardinia" (Italian: gli Stati del Re di Sardegna).

[16] Modern-day historians use the term Savoyard state to indicate this entity, which is an example of composite monarchy where many different and distinct territories are united in a personal union by having the same ruler.

At the time, what is known today as Piedmont, as part of the Kingdom of Italy within the Holy Roman Empire, was subdivided into several marks and counties.

Because the Kingdom of Sardinia had existed since the 14th century, the exchange allowed Victor Amadeus to retain the title of king in spite of the loss of Sicily.

During the Savoyard period as a composite state, Italian, which alongside French had already been made official in the peninsula since the 16th century via the Rivoli Edict,[21][22][23] was introduced to Sardinia in 1760.

The Kingdom of Sardinia's attempt of promotion of a unitary language was incisive,[25] and also the replacement of Spanish with Italian has been described as a "revolution of ideas".

On 6 December 1798 General Joubert occupied Turin and forced Charles Emmanuel IV to abdicate and leave for the island of Sardinia.

[32] In 1814, the Crown of Savoy enlarged its territories with the addition of the former Republic of Genoa, now a duchy, and it served as a buffer state against France.

[35] Earlier in 1847, the island of Sardinia, a Piedmontese dependency for more than a century, lost its own residual autonomy to the peninsula through the Perfect Fusion issued by Charles Albert.

As a result, the kingdom's fundamental institutions were deeply transformed, assuming the shape of a constitutional and centralized monarchy on the French model; under the same pressure, Charles Albert declared war on Austria.

Like all the various duchies and city-states on the Apennine peninsula and associated islands, the Kingdom of Sardinia was troubled with political instability under alternating governments.

After a short and disastrous renewal of the war with Austria in 1849, Charles Albert abdicated on 23 March 1849 in favour of his son Victor Emmanuel II.

In 1852, a liberal ministry under Count Camillo Benso di Cavour was installed and the Kingdom of Sardinia became the engine driving Italian unification.

The Kingdom of Sardinia took part in the Crimean War, allied with the Ottoman Empire, Britain, and France, and fighting against Russia.

Following the bloody battles of Magenta and Solferino, both French victories, Napoleon thought the war too costly to continue and made a separate peace behind Cavour's back in which only Lombardy would be ceded.

This alarmed Napoleon, who feared a strong Savoyard state on his south-eastern border and he insisted that if the Kingdom of Sardinia were to keep the new acquisitions they would have to cede Savoy and Nice to France.

Cavour believed that economic progress had to precede political change, and stressed the advantages of railroad construction in the peninsula.

He experimented with different agricultural techniques on his estate, such as growing sugar beets, and was one of the first Italian landowners to use chemical fertilizers.

[8] The Perfect Fusion (Italian: Fusione perfetta) was the 1847 act of the Savoyard King Charles Albert of Sardinia which abolished the administrative differences between the mainland states and the island of Sardinia, in a fashion similar to the Nueva Planta decrees between the Crown of Castile and the realms of the Crown of Aragon between 1707 and 1716 and the Acts of Union between Great Britain and Ireland in 1800.

Even though it suffered deep modifications, especially during the fascist government of Benito Mussolini (who ruled with the tacit approval of King Victor Emmanuel III), the Statute lasted mostly unaltered in the structure until the implementation of the republican constitution in 1948, which superseded several primary features of the document, with specific regard to those of monarchical nature.

Eventually, King Charles Albert of Savoy adopted from Revolutionary France the Italian tricolor, surmounted by the Savoyard shield, as his flag.