Italy
Naples and Sicily in the 15th Century
Queen Giovanna II (1414-1435)
Giovanna had a pretty wild and tempestuous rule, with a succession of favorites at court that were so strong one of them even forced her own husband to return to France. She opposed Martin V more than once, though she was eventually reconciled.
In 1420 Louis III of Provence invaded the Regno, supported by Pope Martin V and by Sforza. Queen Giovanna appealed to Alfonso of Aragon (and Sicily) who was in the field in Sardinia at the time. He gallantly came to her rescue. The condotierre Muzio Attendolo Sforza and the Colonna (Martin V) fought for Louis, while the Orsini (based at TarantoO sided with Aragon and the other great southern condotierre, Braccio da Montane. By 1424 Giovanna had survived but only by recognizing Louis as her heir, turning away from Alfonso, and Braccio had died in battle.
Alfonso the Wise
In 1435 came a series of extraordinary events. First, both Louis and Giovanna died within weeks of each other. She designated René, Louis' brother, her heir, but he was a prisoner of Burgundy at the time, so the throne was effectively open. The anti-French factions persuaded Alfonso to try again. He did, but Genoa came in on the other side. The city saw Aragon and Catalonia as its principal rival in the western Mediterranean. Genoa won a huge naval victory at Ponza, capturing not only Alfonso but his two brothers as well. Incredibly, Alfonso managed to persuade Filippo Maria Galeazzo (Genoa's overlord at the time) to take him on as an ally and together to conquer all of Italy. Alfonso was freed and began a methodical conquest of Naples, which he completed when he entered the city in 1442.
The Aragonese dynasty was an odd one. Aragon actually had a virtual empire in the western Mediterranean, and Naples became its headquarters. Spanish officials staffed all the "imperial" offices, while Neapolitan aristocrats continued to hold all the local offices. There were two governments, side-by-side, in an uneasy relationship that was amicable so long as the money flowed. For his part, Alfonso was glad to grant to the nobles whatever titles and exemptions they wanted, so long as they kept quiet and kept paying.
King Ferrante
1459 Ferrante became king of Naples. He was immediately faced with widespread rebellion but eventually won. He destroyed the Orsini Prince of Taranto and distributed its estates to his followers.
1480 the Ottomans invaded Italy and capture Otranto. For a time, all of Italy trembled, but when the Sultan died the next year, the Ottomans withdrew having done little permanent damage. Ferrante died in August 1484, exhausted from the constant warfare that had begun when he participated in the Pazzi revolt.
1485-86 a major revolt by the barons of Naples just barely fails. The Aragonese dynasty held to the moment. But powerful forces were gathering in the north that would overwhelm Il Regno, for in 1494 the French invaded and Italy was in for forty years of war. Most of it was fought in the north, but the south was repeatedly dragged into the conflict and knew no peace.
Conclusion
The narrative of these two centuries is a dismal one for southern Italy. The Kingdom had once seemed to show much promise under the Hohenstaufen. It had been wealthy and relatively peaceful, and it was certainly well positioned to share in the booming Mediterranean trade. But for nearly three centuries, from the Sicilian Vespers in 1284 to the Peace of Cateau-Cambresis in 1559, the Kingdom (which for much of the time was actually two kingdoms) was tossed about by outside forces and tumbled incessantly by its own barons. Naples had been a coveted prize throughout the period we are studying. Afterward, it became a backwater, peaceful only because it was neglected.