The Byzantine army was a military force organized by the Byzantine Empire between 330 AD and 1453 AD. Originally modeled after the Roman army, this force evolved over time to combat threats to the empire. The army’s size expanded and contracted through the life of the empire and fought in several major campaigns in the area around the Mediterranean Sea. For much of the empire’s existence, the Byzantine army was one of the strongest and best organized military forces in the region.
The Byzantine army was a direct successor to the Roman armies that occupied the eastern half of the empire before its division in the early fourth century AD. Early Byzantine forces used a legion system of heavy infantry supplemented with light cavalry and archers. Barbarians and foreign mercenaries made up a significant portion of the army throughout its existence.
As time passed, the Byzantine army was reorganized to face a growing Persian military threat, eventually abandoning the legion system and relying more on heavy cavalry in the field. The army also adopted new weapons and better defensive armor. Under Justinian I, the Byzantine military was able to retake much of the territory held by the Roman Empire in North Africa and Southern Europe, although this period would represent the high point of the empire’s expansion.
After Justinian’s death, the empire slowly began to contract, eventually spurring a re-organization of the military administration. The empire was divided into five themes based on the previous armies, and land inside these themes was given to soldiers in return for service, similar to the European feudal system. Subsequent revolts led to the establishment of a professional military based in Constantinople and known as the tagma. This period saw the army adopt a largely defensive posture against hostile neighbors and a gradual decline in effectiveness.
Under the Komnenian dynasty in the 11th and 12th centuries, the army was re-constituted with professional soldiers from the capital and levied troops from the surrounding provinces. The Byzantine army of this period placed an emphasis on training and equipment. It also became highly centralized and dependent on imperial leadership. This dependence would eventually lead to the end of the empire in 1453, because the succeeding dynasty was unable to provide strong military guidance.
While the Byzantine army enjoyed mixed success during its long life, it did manage to re-invent itself to meet new challenges and to defend the city of Constantinople from successive waves of invaders for more than 1,000 years. During this time, the army was able to project power into North Africa, Europe and the Middle East. Despite its eventual downfall, the Byzantine army represented one of the most powerful military forces of its time.