The Perfect Fusion (Italian: Fusione perfetta) was the 1847 act of the Savoyard king Charles Albert of Sardinia which abolished the administrative differences between his realms, including Savoy, Sardinia and Piedmont.
The Kingdom of Sardinia had become a possession of the House of Savoy in 1720, and it had continued to be ruled as during the ages of the Spanish Empire.
This situation became a problem for some Sardinian notables when liberal reforms began to be put in force in Turin, and some of them started to see their separate legal system as a handicap more than a privilege. King Charles Albert solved the problem by transforming his dominions into a single, centralized state.
A new legal system entered into force in Sardinia, and the last viceroy, Claudio Gabriele de Launay, left Cagliari on 4 March 1848. The island was divided into three provinces ruled by their prefects, as had happened in Piedmont in 1815.
The fusion was supposed to spur commercial development in Sardinia and, by 1861, according to William S. Craig (then British consul-general at Cagliari), increase the kingdom's importance; however, the island lost what little autonomy it had in the process, rasing the so-called "Sardinian Question": most of the Sardinian unionists, including its leader Giovanni Siotto Pintor, would later regret it.