Editing Constantine XI Palaiologos (section)

=== Despot at Mystras ===
[[File:Mystras palace 1.jpg|left|thumb|The Despot's Palace in [[Mystras]], from which Constantine ruled as [[Despot of the Morea]] 1443–1449]]
With Theodore and Demetrios gone, Constantine and Thomas hoped to strengthen the Morea. By this time, the Morea was the cultural center of the Byzantine world and provided a more hopeful atmosphere than Constantinople. Patrons of art and science had settled there at Theodore's invitation and churches, monasteries, and mansions continued to be built. The two Palaiologos brothers hoped to make the Morea into a safe and nearly self-sufficient principality. The philosopher [[Gemistus Pletho]], employed in Constantine's service, said that while Constantinople had once been the New Rome, Mystras and the Morea could become the "New [[Sparta]]", a centralized and strong Hellenic kingdom in its own right.{{Sfn|Nicol|1992|p=|pp=21–22}}

One of the projects of the brothers' plan to strengthen the despotate was the reconstruction of the Hexamilion wall, which was destroyed by the Turks in 1431. Together, they completely restored the wall by March 1444. The project impressed many of their subjects and contemporaries, including the Venetian lords in the Peloponnese, who had politely declined to help with its funding. The restoration had cost much in both money and manpower; many of the Moreot landowners had momentarily fled to Venetian lands to avoid financing the venture while others had rebelled before being compelled through military means.{{Sfn|Nicol|1992|p=|pp=23–24}} Constantine attempted to attract the loyalty of the Moreot landowners by granting them both further lands and various privileges. He also staged local athletic games, where young Moreots could run races for prizes.{{Sfn|Nicol|1992|p=27}}
[[File:Battle of Varna 1444.PNG|thumb|The [[Crusade of Varna]], sent to aid the [[Byzantine Empire|Byzantines]] against the [[Ottoman Empire|Ottomans]], was crushed by Sultan [[Murad II]] at the [[Battle of Varna]] (pictured) in 1444]]
In the summer of 1444, perhaps encouraged by news from the west that [[Crusade of Varna|a crusade]] had set out from Hungary in 1443, Constantine invaded the Latin [[Duchy of Athens]], his direct northern neighbor and an Ottoman vassal. Through Sphrantzes, Constantine was in contact with Cardinal [[Julian Cesarini]], who along with [[Władysław III of Poland]] and Hungary was one of the leaders of the crusade. Cesarini was made aware of Constantine's intentions and that he was ready to aid the crusade in striking at the Ottomans from the south. Constantine swiftly captured Athens and [[Thebes, Greece|Thebes]], which forced Duke [[Nerio II Acciaioli]] to pay the tribute to him instead of the Ottomans. The recapture of Athens was seen as a particularly glorious feat. One of Constantine's counsellors compared the despot to the legendary ancient Athenian general [[Themistocles]]. Although the crusading army was destroyed by the Ottoman army led by Murad II at the [[Battle of Varna]] on 10 November 1444, Constantine was not deterred. His initial campaign had been remarkably successful and he had also received foreign support from Duke [[Philip the Good]] of Burgundy, who had sent him 300 soldiers. With the Burgundian soldiers and his own men, Constantine raided central Greece as far north as the [[Pindus]] mountains in [[Thessaly]], where the locals happily welcomed him as their new lord. As Constantine's campaign progressed, one of his governors, [[Constantine Kantakouzenos]], also made his way north, attacked Thessaly, and seized the town of [[Lidoriki]] from the Ottomans. The townspeople were so excited at their liberation that they renamed the town to Kantakouzinopolis in his honor.{{Sfn|Nicol|1992|p=|pp=27–29}}

Tiring of Constantine's successes, Murad II, accompanied by Duke Nerio II of Athens, marched on the Morea in 1446, with an army possibly numbering as many as 60,000 men.{{Sfn|Nicol|1992|p=30}} Despite the overwhelming number of Ottoman troops, Constantine refused to surrender his gains in Greece and instead prepared for battle.{{Sfn|Hellebuyck|2006|p=45}}{{better source needed|date=March 2023}} The Ottomans quickly restored control over Thessaly; Constantine and Thomas rallied at the Hexamilion wall, which the Ottomans reached on 27 November.{{Sfn|Nicol|1992|p=30}} Constantine and Thomas were determined to hold the wall and had brought all their available forces, amounting to perhaps as many as 20,000 men, to defend it.{{Sfn|Runciman|2009|p=76}} Although the wall might have held against the great Ottoman army under normal circumstances, Murad had brought cannons with him and by 10 December, the wall had been reduced to rubble and most of the defenders were either killed or captured; Constantine and Thomas barely escaped the catastrophic defeat. Turahan was sent south to take Mystras and devastate Constantine's lands while Murad II led his forces in the north of the Peloponnese. Although Turahan failed to take Mystras, this was of little consequence as Murad only wanted to instill terror and did not wish to conquer the Morea at the time. The Turks left the peninsula devastated and depopulated. Constantine and Thomas were in no position to ask for a truce and were forced to accept Murad as their lord, pay him tribute, and promise to never again restore the Hexamilion wall.{{Sfn|Nicol|1992|p=|pp=31–33}}