Alfonso V of Aragon
Born at Medina del Campo, he was the son of Ferdinand I of Aragon and Eleanor of Alburquerque. He represented the old line of the counts of Barcelona through the female line, and was on his father's side descended from the House of Trastamara, the reigning House of Castile. By hereditary right he was king of Sicily and claimed the island of Sardinia for himself, though it was then in the possession of Genoa. Alfonso was also in possession of much of Corsica by the 1420s.
The Duke of Milan, Filippo Maria Visconti, joined the anti-Aragonese coalition. Alfonso requested support from Braccio da Montone, who was besieging Joanna's troops in L'Aquila, but had to set sail for Spain, where a war had broken out between his brothers and the Kingdom of Castile. On his way towards Barcelona, Alfonso destroyed Marseille, a possession of Louis III.
In Milan, however, he impressed his captor with his cultured demeanor and persuaded him to let him go by making it plain that it was not in Milan's interest to prevent the victory of the Aragonese party in Naples. Helped by a Sicilian fleet, Alfonso recaptured Capua and set his base in Gaeta in February 1436. Meanwhile, papal troops had invaded the Neapolitan kingdom, but Alfonso bribed their commander, Cardinal Giovanni Vitelleschi, and their successes waned.
Alfonso, by formally submitting his reign to the Papacy, obtained the consent of Pope Eugene IV that the Kingdom of Naples would go to his illegitimate son Ferdinand. He died in Castel dell'Ovo in 1458, while he was planning the conquest of Genoa. At the time, Alfonso was at odds with Callixtus III, who died shortly afterwards.
Alfonso had been betrothed to Maria of Castile (1401–1458; sister of John II of Castile) in Valladolid in 1408; the marriage was celebrated in Valencia on 12 June 1415. They failed to produce children. Alfonso had been in love with a woman of noble family named Lucrezia d'Alagno, who served as a de facto queen at the Neapolitan court as well as an inspiring muse.