fter their victory at Varna (1444) the Ottomans turned to face the despotes Constantine in the Peloponnese. The latter retreated before the powerful forces of Murad II and decided to fight the final battle by the Hexamilion, at the Isthmus of Corinth. But the Turkish sultan managed to destroy the wall and to overpower the Byzantine forces (December 1446). The Turks invaded the Morea, sacked the Byzantine towns and villages and left taking 60,000 captives. The Sultan, nonetheless, having still to confront Skanderberg and Hunyadi, conceded peace to the Byzantine despotes, who, in return, had to to recognise the Sultan's suzerainty and to pay tribute to him. Instead of turning to face Skanderberg, who continued to wage a guerilla war in the mountains of Albania and was to remain undefeated for many years to come, Murad preferred to deal with Janos Hunyadi of Hungary, who posed a more immediate threat.

Hunyadi, having become the new ruler of Hungary following the death of Ladislas III, undertook an expedition against Murad II. However, at the battle which took place in Kosovo in October 1448, he was forced, after a fierce fight, to yield to the Ottomans. This was the last attempt to oppose Turkish domination. On 31 October the Byzantine Emperor, John VIII, died. As he left no heir, the one called upon to succeed him was the despotes of the Morea, Constantine Dragas. On 6 January 1449 Constantine was crowned Emperor in the Morea and two months later he entered the capital. Left to rule jointly over the Morea were his two brothers, Thomas and Demetrios.