In 1206, the fortress (known as Demotika) was besieged by Bulgarian Tsar Kaloyan, who took advantage of the disintegration of the Byzantine Empire. The fortress was later occupied by the Latin Empire. In 1303, with the re-establishment of Byzantine rule, master builder Constantine Tarchaneiotes strengthened the fortifications. This is supported by Topography of building materials and methods that suggest the occupation by Byzantine forces continued into the later period of the empire.