The Byzantine and the Arab Empires
Then the Romans [Byzantines] also formed up and raised their standards. And so the barbarians [Persians] extended the length of their line, intending to create thereby an impression of a countless multitude on the forces contending in opposition. But the Romans made a deep formation whose density gave it weight, so that the array appeared to he virtually solid and to stand steel-resistant....The barbarians were dismayed at the sight. And so they fired arrows against the Roman companies, so that the sun's rays were hidden by the discharge of missiles, and on account of the furious outpouring of shafts a winged roof appeared to be spread in the air above their heads. The Romans engaged in hand-to-hand combat, resisting the barbarians with spears and swords, cutting short the assault of the missiles' onslaught; hence they rendered the opponents devoid of stratagems. Accordingly a most memorable battle between Romans and Parthians occurred, the Persian host was broken because their ranks were not organized in depth, the rearguard of their armament was at a loss...next, when the opposing force pressed heavily, the barbarians faced destruction and veered away in flight.
Theophylact Simocatta, History, edited by Mary and Michael Whitby ( Oxford, 1986), pp. 94-95. Theophylact, a Byzantine historian of the late sixth century, gave a highly rhetorical description of this unnamed battle of 576 in Armenia.
At the same time as the Western Roman Empire was collapsing, the military forces of the Eastern or Byzantine Empire were recovering, as they were being transformed. The Byzantine military built a record of duration, if not one of brilliant victories, rivaling that of Rome.
The heart of the Byzantine defenses was the city of Constantinople. When Emperor Constantine decided to build a new capital for the Eastern Empire in 330, he placed it on the superb site of the ancient Greek city of Byzantium on the straits between the Black Sea and the Aegean. Situated between the two seas and on the crossroads of Europe and Asia Minor, the city had an excellent position for both military and commercial advantage.