Between 1430-1444, virtually the entire Peloponnese was under the control of the Despot. The new rulers were brothers, Constantine, Demetrios and Thomas Paleologos.
Constantine had been the most active. He is credited with capturing Patras and building the Hexamillion (6 mile) Wall along the Isthmus at Corinth. This infuriated Sultan Murad. He watched as Constantine moved into central Greece fighting with whoever was an enemy of Byzantium. He quickly recaptured Athens and Thebes by 1444.
Frustrated, Sultan Murad attacked the Hexamilion and destroyed it in December 1446. Constantine was lucky to get away. Sixty thousand people were taken prisoner and sold to slavery in Asia Minor. In another epoch, Constantine would have been one of the best military leaders; alas his resources were stretched despite his fighting abilities. In 1451 Constantine was crowned Byzantine emperor in Mystra upon the death of his brother Manuel in Constantinople. He then made his way to the great city, not on a Byzantine ship, for the empire was close to being bankrupt. A sad indication of what remained of this once great empire.