Corsican (corsu or lingua corsa) is an Italo-Dalmatian Romance language spoken and written on the islands of Corsica (France) and northern Sardinia (Italy). Corsican was long the vernacular language alongside Italian, the official language in Corsica until 1859; afterwards Italian was replaced by French, owing to the acquisition of the island by France from Genoa in 1768. Over the next two centuries, the use of French grew to the extent that, by the Liberation in 1945, all islanders had a working knowledge of French. The twentieth century saw a wholesale language shift, with islanders changing their language practices to the extent that there were no monolingual Corsican speakers left by the 1960s. By 1990, an estimated 50% of islanders had some degree of proficiency in Corsican, and a small minority, perhaps 10%, used Corsican as a first language.