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Alfonso the Magnanimous, also known as Alfonso V of Aragon and I of Naples, was the illegitimate son of Ferdinand I, King of Aragon. Ferdinand had an extramarital affair with a woman named Giovanna d'Empúries while married to his first wife, Eleanor of Castile. Alfonso was born in 1416, and despite not being a legitimate heir, he inherited both the Aragonese and Neapolitan thrones.