Holy Roman Emperor Friedrich II had appointed his illegitimate son Enzio king of Sardinia in 1239; the latter would lose the title as soon as 1249, however. In 1284, Genoa defeated Pisa, acquired Corsica, Elba and Sardinia. In 1323, Sardinia was acquired by Aragon, and 1399, Florence bought Corsica from Genoa. (The current ruler, Cosimo de Medici, planned to build up a fleet and becoming a naval power in the Mediterranean.) Later, in the kingdom of Italy, "Prince of the Islands" (Corsica, Sardinia, Sicily, Malta) was a royal title.