This was a continuation of the Roman army. By the end of the 3rd century the wars of conquest were over and the army's role was to protect the imperial borders. Diocletian subdivided the old legions into smaller units, while Constantine withdrew some units from the frontier to create strategically placed mobile reserves, the field armies. The enemy would be checked by a series of hinterland fortifications while the field army closed.
However, this system allowed damage to frontier areas and border troops' morale dropped as they were regarded as second rate. Cities became more heavily fortified and raids and sieges became the prevalent forms of military activity. The disastrous defeat of the eastern field army at Adrianople in 374 allowed the Visigoths to roam the empire, sacking Rome in 410. Under increasing pressure by the end of the 4th century the empire was officially split in two, east and west, with an emperor at the head of each. The western borders were irreparably breached in the early 5th century and Spain and much of Gaul passed beyond effective control.
The western army increasingly used foederates, foreign troops under their own commanders settled on imperial territory in return for military service, but their loyalty was often dubious. The army was also influenced by weapons and equipment copied from steppe peoples. The percentage of horse archers and heavily armoured cavalry was increased, but it was not enough to stop barbarian incursions and by the end of the 5th century the west was effectively lost.
Not until 533 was there a practical attempt at reconquest by the eastern empire. Belisarius recaptured North Africa and Italy. Later southern Spain was retaken but the success was short-lived. Justinian's wars exhausted imperial resources and in the late 6th century the Slavs overran Greece while the eastern frontier witnessed constant warfare. The main enemy was Persia, and the two fought a great war in the early 7th century. By 627 the Byzantines had won, but in 636 they were defeated at Yarmuk by the newly united Arab tribes. Fighting for themselves rather than as desert forces of the two empires, they crushed the Persians and took Egypt, the Levant, and North Africa from the Byzantines. Their navy first threatened Constantinople in 654, Greek fire being one of the weapons used to defeat this and subsequent armadas.
The armies that retreated from the east were organized into themes, four at first. Theme commanders received increased control over civil matters to ensure the local supplies of the army while troops were paid from the revenues of the former imperial estates that they now occupied. This system stemmed the Arab advance, but most of the reconquered western territory was lost, the Lombards taking northern Italy. The northern frontier was overrun by the Bulgarians and the Rus (Vikings) began to raid across the Black Sea to Constantinople (now Istanbul). While the east remained relatively secure, its borders were frequently raided. By the time the scattered troops were mustered, the enemy was already returning home and had to be ambushed in passing while laden with plunder. Increased fortification and more localized control of forces alleviated the problem and this use of fortresses and guerrilla warfare served the empire well for centuries.
Although the theme system maintained the borders it led to many rebellions. Themes were subdivided to limit their commanders' power. Constantine V created new units, the tagmata, which were stationed in and around Constantinople to provide protection for the emperor but they were also crack troops. In 840 Theophilus extended their organization to the themes thus giving them a more effective command and control structure permitting faster mustering and better supervision for training. This system not only protected the empire better but allowed field armies to take the offensive. Reconquest began in earnest under Nicephorus Phocas and by the 11th century the Danube was re-established as the northern frontier and the empire doubled in size from Theophilus' reign.
However, the 11th century also witnessed new enemies. The Pechenegs raided across the Danube up to the walls of Constantinople. The Seljuk Turks were a bigger threat than the Arabs and in 1071 they inflicted a humiliating defeat on the Byzantines at Manzikert, causing the loss of much of Anatolia. The Normans captured southern Italy and Alexios I struggled to keep them from taking Greece. The army began to make increasing use of mercenaries, notably the Varangian (Viking) Guard. Alliances with western powers such as Venice proved financially ruinous and helped bring about a decline in the Byzantine navy, which in turn forced the empire to rely increasingly on such alliances. In 1094 the First Crusade passed through Byzantium en route to the Holy Land. Although supposed to turn recaptured territory over to Alexios, the Crusaders failed to do so. Hungary began to encroach on Byzantine possessions and in 1176 another disastrous defeat was inflicted by the Seljuks at Myriokephalon. The Fourth Crusade, hijacked by the Venetians for their own purposes, sacked Constantinople in 1204 and split the empire into successor states.
Nicaea was destined to be the strongest of these successors and her army, influenced by western organization, successfully held its own. In 1261 the Nicenes recovered Constantinople and the Black Sea coast of Thrace, but it proved to be a costly gain, overstretching their resources. Despite attempts to maintain a professional ‘national’ army, the empire still employed many foreign contingents backed by provincial levies. The Serbs gradually took over Macedonia and then the Ottoman Turks arrived on the scene defeating the Byzantines in 1302. Anatolia, including Nicaea, was lost and the empire, ruined financially, gradually shrank, a process aided by civil wars. In 1354 the Ottomans crossed into Europe splitting what was left of the empire into disparate elements. Constantinople was besieged in 1402 and only saved by the defeat of the Ottomans by Timur at Ankara. The inevitable fate was merely postponed to 1453 when the city finally fell to the cannon of Mehmet II.
Bibliography
- Bartusis, M. C., The Late Byzantine Army: Arms and Society 1204-1453 (Philadelphia, 1992).
- Haldon, J., State, Army and Society in Byzantium (Aldershot, 1995).
- Treadgold, W., The Byzantine Army 284-1081 (Stanford, 1995)
— Stephen McCotter
