The Aragonese Conquest of Naples was a long drawn-out struggle formed of several wars all hinging on the inheritance of the Hohenstaufen lands in Southern Italia. As a point of extreme prestige for Aragon it marked the beginning of almost four hundred years of extraordinarily damaging wars on the Italian peninsula.
The root cause, lay in the forcible usurpation of Naples from the Hohenstaufens by Charles of Bezier.
The Hohenstaufen dynasty had always had a spotty relationship with the papacy going back to Henry IV's investiture crisis of the 1070s. This papal mistrust, usually centering on the family's designs on Italia, continued through to Frederick III's division of the Hohenstaufen lands. In Naples his successor Conrad II was a weak ruler however his elder brother Frederick IV of Arles was a dynamic presence and Urban IV feared if Frederick had his hands on Naples then the rest of Italia would not be far behind. Conrad had a daughter, Isabella, who was married to the relatively minor Count Charles of Bezier. Despite being of modest means himself Charles was well-liked in Naples (less so in Sicily) Pope Urban IV conspired with Charles and on Conrad's death in 1268 Charles usurped the throne from his wife with his blessing. This of course resulted in a war between Naples and Arles which Charles held the upper hand thanks to alliances with Genoa and Pisa which ensured he was protected on the seas whilst he built up Naples' own fleet.The original County of Bézier, nestled in the Languedoc, was technically subject to Aragon and the fact that Charles now would not pay them homage, when his father had, angered James I. Added to that James had a claim to Naples through his Hohenstaufen grandmother. Therefore when Frederick IV came calling for allies in 1268 against Charles and Genoa, James I readily accepted.
The Arelat and Aragonese fleets were soon at sea hoping to deposit a considerable invasion force on Sicily but the relatively powerful Genoese fleet soon put pay to that idea and the original attack faltered. What few troops got through to Sicily were quickly defeated. Instead the allies focused their attentions on a land campaign against Genoa. After the Battle of Ovada in May 1270 Genoa was put to a long siege by Arles. James II petitioned the Hapsburg Emperor Rudolph I for permission to enter Italia with an Aragonese force but was dismissed. He would forge through anyway but his force was much reduced by the time it reached Rome thanks to disease and attacks from Guelph affiliated cities. The attacks against Charles' northern fortresses were quickly rebuffed and James would return home with less than a fifth of the men he went out with, soon to face a series of revolts.Despite instigating an uprising in Sicily, the Sicilian 'Compline', in 1282 (which cost Charles considerable effort to subdue) Aragon had singularly failed to gain a toehold on Sicily or the mainland. Attacks on Sardinia after the Genoese withdrawal were more successful and by 1290 the island was split in half. Peter III was much distracted by matters in the Languedoc, including a French invasion in 1304 and neglected the goal of Naples to a large degree. France had blundered into the war at the behest of the papacy who, vehemently pro-Bezier, accused the Aragonese of attacking Sicily which they claimed was a papal fief and as such urged a crusade against Peter III whom was summarily excommunicated. Still smarting from the failure of the Albigensian Crusade which had ruined French reputation as well as locking it out of southern Francia, Louis X arranged a fresh alliance with Aquitaine and, skirting hostile Auvergne, ploughed into the Languedoc. Though they would capture several cities and Louis X would crown himself King of Majorca (which at that time included Roussillon) a reversal was not far behind. The Aquitanian navy was crushed at the Battle of Les Formigues and, now isolated and forced into a retreat, the French army was almost wiped out at Perpignan. Louis X only escaped thanks to the quick thinking of his retinue.
With the war at a standstill Pope Boniface VIII, a virtual Neapolitan puppet, mediated a peace treaty which lifted the ban on Peter III. This would stand until a pro-Neapolitan revolt swept through the Aragonese half of Sardinia in 1323. James III loaded up his ships and put down the revolt with what some regarded as excessive force. With his own territory pacified he found (or falsified) Neapolitan documents urging the Sardinians to rise up and invaded their half as well. By mid-1234 the entire island was in Aragonese hands. And soon after he had seized Neapolitan Corsica for good measure too. James III pressured the new Queen Regnant of Arles, Beatrice, to accept the seizure of the islands and cede her claim to the throne of Naples to himself. Weakened by war against Burgundy, she would accept. In return Aragon would campaign on behalf of Arles and uphold Beatrice's son Philip's right of succession, shoring up its own hold on the Languedoc in the process.
Another papal mediated treaty in 1346 asked for the islands to be returned, in full, to Naples but James III simply ignored it. In this he was supported by several other states whose relations with Rome were slowly deteriorating. The papacy itself was much compromised by its unflinchingly pro-Naples stance. Many argued it had simply swapped potential Hohenstaufen servitude for actual Bezier domination, and alongside accusations of various corruptions, in 1349 Clement VI, a Frenchman, was forced to flee an angry Roman mob. As he sat out his exile in Genoa and then eventually Tours, another pope, Anastasius V, was elected by the Roman populace. This anti-pope quickly called for the removal of the newly crowned Charles III from Naples, offering the throne to several European houses. The future William I of Wessex declined, as did of Conan VIII of Brittany and Peter I of Leon, all citing the huge cost involved and the disruption caused to their own lands by the Black Death. James III of Aragon accepted the offer however, keen to reignite a legitimate war. However the depth of the papal schism, and the civil war in Germany, stopped James from an outright attack, fearing the consequences of an excommunication. It would be left to his nephew John II, previously ruler of Majorca, to restart the war after a change of leadership in Germany.Emperor Olaf, having defeated the Florentine Army at Vernio in 1372, now looked to cement a hold on Italian affairs and waded into the ongoing papal schism by promoting yet another pope, John XXIII. At Olaf's urging this pope also granted Aragon a free hand in Naples and recognised it as rightful heirs to the Hohenstaufen dynasty there. With two popes and the emperor on their side it immediately reinvigorated the war and John II collected together the largest army so far. A naval battle off Malta put pay to a direct invasion of Sicily but Neapolitan Athens fell in 1375. Later the same year mercenaries had captured the fortress of Marsala was captured and from then on, year upon year, Aragonese dominance of Sicily grew until by 1381 it had wrested all of its forts from Bezier hands. By this point however the Beziers did not just hold Naples, they also ruled over Hungary and Poland. John I would transport a huge Hungarian army to Naples to ward off Aragon's attacks but all this did was to stir up anger and the plague among the populace. Though these Hungarians would not prevent the loss of Sicily they would in time prevent Aragonese forces from gaining a quick victory on the mainland.
John I's daughter Adelaide and her husband Wenceslaus would continue the operation and after Wenceslaus' coronation as Holy Roman Emperor, and the end of the papal schism, much of Aragon's support from elsewhere in Europe disappeared. Or at least it shifted elsewhere. Alongside France and Denmark it loosely formed an anti-Luxembourg bloc with Rupert of Wittelsbach to try and stymie Wenceslaus' ambitions and also pledged moral support to Aragon. A firm Danish alliance would be cemented by the marriage of Valdemar II to John II's daughter Eleanor in 1384.Although Wenceslaus' attentions, and the Hungarian forces were briefly shifted to Northern Italia in a spirited but fruitless attempt to recreate a 'Kingdom of Lombardy', the conquest of mainland Naples would not be a foregone conclusion. John II had expected to capture Naples by 1390, in fact it would take him and his son Peter IV another forty-one years to achieve. This was partly down to other pressing matters.
In 1388 opportunistic Italian nobles raised a mercenary army and seized Athens, setting up a independent duchy. This was partly supported by Byzantium, which saw the Italians in the Peloponnese as a bulwark against the Turks, and were happy for them to accept Venice's protection. Aragon would endure several years fruitless attempts to recapture it, with frequent naval battles against Venice. Eventually it accepted the loss and as a result Byzantium and Venice, which were tiring of Bezier domination of the Adriatic anyway, came to terms and accepted Aragon's claim to Naples.
In 1401 Sardinia revolted, with its four dominant family dynasties exploding into violence against one another whilst rounding on Catalan merchants and castellans. The island's reconquest would occupy the first years of Peter IV's reign, as would a series of 'crusades' to North Africa against Morocco and a petty war against Castile. Above all this the dogged resilience of the Bezier kings stopped any further erosion of their Neapolitan holdings. With support from the Luxembourgs and their Hungarian possessions Aragon was repeatedly put on the back foot. Massive invasions of Sicily coupled with concerted Sicilian unrest obliged both John II and Peter IV to spend most of their time fighting on their own turf.Slowly however the tide turned. With Aragonese and Genoan shipping increasingly dominant and the other parts of the kingdom settling down more. The Luxembourgs were increasingly embattled in Germany and after the Hussite Wars erupted in Bohemia they virtually stopped supporting Naples. Pope John XXIV excommunicated Charles IV in 1418 for 'plotting against him' and Charles's authority abruptly crumbled. Finally in 1420 Aragon captured Cosenza, a noted centre of anti-Bezier revolt and the rest of Calabria swiftly fell. Within a year Charles' rule was confined to Naples itself. On Christmas Day 1421 diplomats offered Charles an exit (into Aragonese imprisonment) if he gave up the city quietly but they were rebuffed. It would take another six months before the city's populace revolted and executed the last of the Beziers. Charles' corpse was unceremoniously dumped outside the walls but Peter magnanimously had him buried with full rites.
Peter rode into Naples on 1st July 1422 at the head of a huge Aragonese-Italian force and was crowned King of Naples by its archbishop on 6th July. After this he would travel back to Cosenza, erecting a small chapel at the Visigothic king Alaric I's supposed resting place. Peter was now master of a considerable realm stretching from the Pyrenees to the heel of Italia with the Aragonese merchant fleet controlling much of the western Mediterranean. Catalan was increasingly the language of choice for merchants and the Aragonese Silver Ducat the monetary standard. Now having fulfilled Aragon's purpose for much of the previous century Peter planned still greater feats. He advocated immediately retaking the Greek possessions lost to pirates and Italian opportunists. A classics scholar, he planned a crusade to Tunisia to 'retake Carthage' and dreamt of turning the Western Mediterranean into an 'Aragonese Lake'.Yet this new Pax Aragona would barely last a year. The Aragonese crown was not a unitary state and nor did Peter rule all of his territories in union (in stark contrast say to the ever-expanding Luxembourg realm). Instead as his predecessors had done he set up his brothers and nephews as local rulers or sub-kings. This made sense from an administrative perspective but succession was a minefield. When Peter died suddenly in August 1423 his empire abruptly fell apart. While Aragon fell to his daughter Joanna, the rest went to her cousins; Naples to James I, Sicily and Sardinia to Martin I. Even Majorca and its nominal Languedoc territory rebelled once more.
Undeterred, Joanna and her successors would effectively commit Aragon to the task of reconquering all the lands it had spent so long amassing, a job which would take another 250 years and remain unfinished. As in the final years of the war its efforts to retake Naples would not go unopposed and increasingly other nations circled. The wars over Italia would wreck havoc on the peninsula and suck in the armies of half of Europe.
The long nature of the wars appears to have had an effect on the Aragonese national character. Even now short-term opportunism is regarded almost as a cardinal sin. Some historians have attributed its efforts during the Fifty Years War to a belief that in the long-term, no matter what defeats were inflicted on its army, or however many times bankruptcy loomed, it would eventually succeed.