Alfonso V of Aragon Alfonso the Magnanimous KG ( also Alphonso ; ; 1396 – 27 June 1458 ) was the King of Aragon ( as Alfonso V ) , Valencia ( as Alfonso III ) , Majorca , Sardinia and Corsica ( as Alfonso II ) , Sicily ( as Alfonso I ) and Count of Barcelona ( as Alfonso IV ) from 1416 , and King of Naples ( as Alfonso I ) from 1442 until his death . He was one of the most prominent figures of the early Renaissance and a knight of the Order of the Dragon . Biography . 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 . In 1421 the childless Queen Joan II of Naples adopted and named him as heir to the Kingdom of Naples , and Alfonso went to Naples . Here he hired the famous condottiero Braccio da Montone with the task of reducing the resistance of his rival claimant , Louis III of Anjou , and his forces led by Muzio Attendolo Sforza . Pope Martin V supporting Sforza , Alfonso switched his religious allegiance to the Aragonese antipope Benedict XIII . When Sforza abandoned Louis ' cause , Alfonso seemed to have all his problems solved ; however , his relationship with Joan suddenly worsened , and in May 1423 he had her lover , Gianni Caracciolo , a powerful figure in the Neapolitan court , arrested . After an attempt to arrest the queen herself had failed , Joan called on Sforza who defeated the Aragonese militias near Castel Capuano in Naples . Alfonso fled to Castel Nuovo , but the help of a fleet of 22 galleys led by Giovanni da Cardona improved his situation . Sforza and Joan ransomed Caracciolo and retreated to the fortress of Aversa . Here she repudiated her earlier adoption of Alfonso and , with the backing of Martin V , named Louis III as her heir instead . The Duke of Milan , Filippo Maria Visconti , joined the anti - Aragonese coalition . Alfonso requested support from Braccio da Montone , who was besieging Joan ' 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 late 1423 the Genoese fleet of Filippo Maria Visconti moved in the southern Tyrrhenian Sea , rapidly conquering Gaeta , Procida , Castellammare and Sorrento . Naples , which was held by Alfonso ' s brother , Pedro de Aragon , was besieged in 1424 by the Genoese ships and Joan ' s troops , now led by Francesco Sforza , the son of Muzio Sforza ( who had met his death at L ' Aquila ) . The city fell in April 1424 . Pedro , after a short resistance in Castel Nuovo , fled to Sicily in August . Joan II and Louis III again took possession of the realm , although the true power was in the hands of Gianni Caracciolo . An opportunity for Alfonso to reconquer Naples occurred in 1432 , when Caracciolo was killed in a conspiracy . Alfonso tried to regain the favour of the queen , but failed , and had to wait for the death of both Louis ( at Cosenza in 1434 ) and Joan herself ( February 1435 ) . In her will , she bequeathed her realm to René of Anjou , Louis III ' s younger brother . This solution was opposed by the new pope , Eugene IV , who nominally was the feudal lord of the King of Naples . The Neapolitans having called in the French , Alfonso decided to intervene and , with the support of several barons of the kingdom , captured Capua and besieged the important sea fortress of Gaeta . His fleet of 25 galleys was met by the Genoese ships sent by Visconti , led by Biagio Assereto . In the battle that ensued , Alfonso was defeated and taken prisoner . 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 . In the meantime , René had managed to reach Naples on 19 May 1438 . Alfonso tried to besiege the city in the following September , but failed . His brother Pedro was killed during the battle . Castel Nuovo , where an Aragonese garrison resisted , fell to the Angevine mercenaries in August 1439 . After the death of his condottiero Jacopo Caldora , however , René ' s fortune started to decline : Alfonso could easily capture Aversa , Salerno , Benevento , Manfredonia and Bitonto . René , whose possession included now only part of the Abruzzi and Naples , obtained 10 , 000 men from the pope , but the cardinal leading them signed a truce with Alfonso . Giovanni Sforza came with a reduced corps , as troops sent by Eugene IV had halted his father Francesco in the Marche . Alfonso , provided with the most impressive artillery of the times , again besieged Naples . The siege began on 10 November 1441 , ending on 2 June the following year . After the return of René to Provence , Alfonso easily reduced the remaining resistance and made his triumphal entrance in Naples on 26 February 1443 , as the monarch of a pacified kingdom . In 1446 he also conquered Sardinia . 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 . His Spanish possessions were ruled for him by his brother John , later king John II of Aragon . Sicily and Sardinia were also inherited by his brother . Alfonso was also a powerful and faithful supporter of Skanderbeg , whom he decided to take under his protection as a vassal in 1451 , shortly after the latter had scored his second victory against Murad II . In addition to financial assistance , he supplied the Albanian leader with troops , military equipment , and sanctuary for himself and his family if such a need should arise . This was because in 1448 , while Skanderbeg was victoriously fighting off the Turkish invasions , three military columns , commanded by Demetrio Reres along with his sons Giorgio and Basilio , had been dispatched to help Alfonso V defeat the barons of Naples who had rebelled against him . Family . 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 . Genealogical records in the Old Occitan Chronicle of Montpellier in " Le petit Thalamus de Montpellier " indicate that Alphonso ' s relationship with his mistress , Giraldona Carlino , produced three children : Giraldona was the daughter of Enrique Carlino and his wife , Isabel . Art and administration . Like a true prince of the Renaissance , he favoured men of letters whom he trusted to preserve his reputation to posterity . He founded the Academy of Naples under Giovanni Pontano , and for his entrance into the city in 1443 had a magnificent triumphal arch added to the main gate of Castel Nuovo . This edifice , considered the most important civil piece of art of the time , was designed by Francesco Laurana . Alfonso ' s devotion to the classics was exceptional even in his day . For example , he halted his army in pious respect before the birthplace of a Latin writer , carried texts of Livy or Caesar on his campaigns , and his panegyrist Panormita even stated that the king was cured of an illness when a few pages of Quintus Curtius Rufus ' history of Alexander the Great were read to him . However , the classics had not refined his taste , for he was amused by setting itinerant scholars , who swarmed to his court , to abuse one another in the indescribably filthy Latin scolding matches which were then the fashion . After his conquest of Naples in 1442 , Alfonso ruled by his mercenary soldiers and mercenary men of letters . In his Italian kingdom , he maintained the former political and administrative institutions . A unified General Chancellorship for the whole Aragonese reign was set in Naples , although the main functionaries were of Aragonese nationality . Apart from financial , administrative and artistical improvements , his other accomplishments in the Sicilian kingdom include the restoration of the aqueducts , the drainage of marshy areas , and the pavement of streets . Connection with Ethiopia . Alfonso was the object of diplomatic contacts from the empire of Ethiopia . In 1428 , he received a letter from Yeshaq I of Ethiopia , borne by two dignitaries , which proposed an alliance against the Muslims and would be sealed by a dual marriage that would require the Infante Peter to bring a group of artisans to Ethiopia where he would marry Yeshaq ' s daughter . In return , Alfonso sent a party of 13 craftsmen , all of whom perished on the way to Ethiopia . He later sent a letter to Yeshaq ' s successor Zara Yaqob in 1450 , in which he wrote that he would be happy to send artisans to Ethiopia if their safe arrival could be guaranteed , but it probably never reached the Emperor .