Corsican (corsu or lingua corsa) is a Romance language within the Italo-Dalmatian subfamily and is closely related to the Italian language. It is spoken and written on the islands of Corsica (France) and northern Sardinia (Italy). Corsican was long the vernacular 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 the Republic of 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 20th 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 1995, an esti