Byzantine Battle Tactics - Brief Structural History

Brief Structural History

Over the course of its long history, the armies of Byzantium were reformed and reorganized many times. The only constants in its structure were its complexity and high levels of professionalism. However, the Empire's military structure can be broadly divided into three periods: East Roman, Thematic and Tagmatic.

At the fall of the Western Empire in 476, the Byzantine army was simply the surviving, eastern half of the Late Roman army. Though structurally very similar to its western counterpart, it differed in several important ways notably: It had more and heavier cavalry, more archers and other missile troops and fewer Foederati. These differences may have been contributing factors to the eastern empire's survival. It was with this East Roman army, that much of the western empire was reconquered in the campaigns of the generals Belisarius and Narses. It was during this time, under Emperor Justinian I, that the revitalized empire reached its greatest territorial extent and the army its greatest size of over 330,000 men by 540. Later, under the general and Emperor Heraclius, the Sassanid Empire of Persia was finally defeated.

Late in Heraclius' reign, however, a major new threat suddenly arose to the empire's security in the form of the Saracens (Mohammedans or Muslims under the Rashidun and Umayyad Caliphates). Spurred on by their new religion, Islam, which demanded the subjugation of the world or its conversion to dar al-Islam, driven by a still-strong tribal warfare mentality, these invaders rapidly overran many of the empire's wealthiest and most important regions, especially Syria, the Levant and Egypt. This new challenge, which seriously threatened the empire's survival, compelled Heraclius and his immediate successors, in the mid-7th century, to undertake a major reform of the Byzantine military system to provide for a more cost effective local defense of its Anatolian heartland. The result was the theme system, which served as both administrative and military divisions, each under the command of a military governor or strategos.

The theme was a division-sized unit of around 9,600, stationed in the theme (administrative district) in which it was raised and named for. The themes were not simply garrison troops, however, but mobile field forces capable of supporting neighboring themes in defensive operations, or joining together to form the backbone of an imperial expeditionary force for offensive campaigns. It was under this new system that the Byzantine army is generally considered to have come into its own, distinct from its late Roman precursor. The Thematic system proved to be both highly resilient and flexible, serving the empire well from the mid-7th through the late 11th centuries. Not only did it hold back the Saracens, but some of Byzantium's lost lands were recaptured. The thematic armies also vanquished many other foes including the Bulgars, Avars, Slavs and Varangians, some of whom eventually ended up in the service of Constantinople as allies or mercenaries.

In addition to the themes, there was also the central imperial army stationed in and near Constantinople called the Tagmata. The tagmata were originally battalion-sized units of guards and elite troops who protected the emperors and defended their capital city. Over time, though, their size increased to that of regiments and brigades. The number of tagmata grew as well. The term, thus, became synonymous with the central field army. Due to growing military pressures together with the empire's shirking economic and manpower base, the themes began to decline. As they did so, the size and importance of the tagmata increased, due also to growing fears of the emperors over the potential dangers the strategoi and their themes posed to their power.

The final, fatal blow to the thematic army occurred in the aftermath of the disaster at the Battle of Manzikert in 1071, when a new enemy, the Seljuk Turks, overran most of Asia Minor along with most the empire's themes. Once again, the empire was forced to adapt to a new strategic reality with reduced borders and resources. Under Emperor Alexios I Komnenos the themes were done away with and the military restructured around the tagmata, some of which were stationed in the provinces, but the majority usually remained near Constantinople when not on campaign. Tagmata would henceforth take on yet a third meaning as a generic term for a standing military unit of regimental size or larger.

This tagmatic army, which includes those of the Komnenian and Palaiologan dynasties, would serve the empire in its final stages from the late 11th to the mid-15th centuries, a period longer than the entire lifespans of many other empires. The tagmatic armies would also prove resilient and flexible, even surviving the near destruction of the empire in the aftermath of the fall of Constantinople to the Fourth Crusade in 1204. They would eventually retake the capital for Emperor Michael VIII Palaiologos in 1261, and though reduced by then to a small force, barely exceeding 20,000 men at most, would continue to defend the empire ably until the fall of Constantinople to the Ottoman Turks in 1453. In no small part due to increased reliance on mercenaries from the Latin west, the later tagmatic armies would come to resemble those of western Europe at the time, more than their Roman, Greek or Near-Eastern antecedents.