Kingdom of Sardinia (1720–1861)
The Kingdom of Sardinia is a term used to denote the Savoyard state from 1720 until 1861, which united the island of Sardinia with the mainland possessions of the House of Savoy. Before 1847, only the island of Sardinia proper was part of the Kingdom of Sardinia, while the other mainland possessions (principally the Duchy of Savoy, Principality of Piedmont, County of Nice, Duchy of Genoa and others) were held by the Savoys in their own right, hence forming a composite monarchy and a personal union which was formally referred to as the "States of His Majesty the King of Sardinia". This situation was changed by the Perfect Fusion act of 1847, which created a unitary kingdom. Due to the fact that Piedmont was the seat of power and prominent part of the entity, the state is also referred to as Sardinia-Piedmont or Piedmont-Sardinia and sometimes erroneously as the Kingdom of Piedmont. 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 1720 Treaty of The Hague, the island of Sardinia and its title of Kingdom were ceded by