While the Jutes, the Angles and the Saxons (coming from northern Germany and Denmark) invaded the
British Islands; while the Franks established themselves in Gaul; while the Visigoths dominated Spain and the Ostrogoths and Lombards occupied Italy, the eastern part of the Roman empire survived and considered itself the one and only Roman heir. From its capital, Constantinople (also called Byzantium, today Istanbul in Turkey), the Oriental Empire dominated the Balkans, Greece, Syria, Egypt and Cyrenaica (today Libya). The emperor Justinian (527-565) consolidated his power, codified the Roman right, and reformed the administration and the Church. Intending to re-create the whole Roman empire, Justinian took northern Africa, the great Mediterranean islands, southern Italy and southern Spain. But Justinian’s conquests were lost by his successors. The Byzantine Empire was weakened and reduced to Greece, Anatolia and a part of the Balkans; nevertheless it retained its prestige and power until 1453, when the city of Constantinople was taken by the Turks.
Byzantine fortifications, notably those of Constantinople, would have a great influence on western military architecture during and after the Crusades. Situated on a promontory, Constantinople was heavily fortified on the land front by the emperor Theodosius II between 408 and 450. The formidable fortifications of Constantinople were composed of three concentric walls, including a ditch 18 m wide and 6.5 m deep, dominated by a crenellated wall 5.5 m high, reinforced by buttresses. About fifteen meters behind this was a second crenellated wall 8 m high and 2 m thick, along with square flanking towers. Behind this, a
Ground plan of Autun ( France). Situated in Saone-et-Loire (Burgundy) on the river Ar-roux, Autun was created in 10 BC by the Roman emperor Augustus (whence its name Augusturum). The prosperous Gallo-Roman town, though playing no significant military role, was fitted with fortifications which enhanced its prestige and wealth. Enclosing a surface of 200 hectares, these fortifications were composed of a crenellated wall 6 km in perimeter, 2.5 m thick and 11 m high including 52 high half-circular towers, four main gates and six secondary posterns. Autun was ravaged by the Vandals, by the Franks in 674, by the Moors in 731, and by the Norsemen in 895. During the invasions, the town was in full decay, abandoned and reduced to a small fortified castrum on the southern hill. In the 12th century it became again a prosperous city which was enlarged and fortified with an enceinte and a circular donjon called the Tour (tower) Saint-Leger (or Tour des Ursulines). The ground plan shows the Roman fortifications (AA) in the 1st century with the Arroux gate (1), the Saint-Andrea gate (2), the theater (3), the Rome gate (4). (B) is the 6th century castrum with the Saint-Lazare cathedral and the episcopal residence. (CC) is the medieval enceinte from the 12th century with the Ursulines dungeon (5) and the Saint-Andoche gate (6). Note that the medieval city, though prosperous and protected by the dukes of Burgundy, was much smaller than the ancient Roman town.
World History
