The Byzantine army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine navy. A direct descendant of the Roman army, the Byzantine army maintained a similar level of discipline, strategic prowess and organization. It was among the most effective armies of western Eurasia for much of the Middle Ages.The early Byzantine army received a mixed diet of victory and defeat - consequently the cavalry arm became more prominent as the legion system disappeared in the early 7th century. Later reforms reflected some Germanic and Asian influences^[1] - with every encounter against a ferocious opponent the Byzantines would find a new source of excellent mercenaries with Huns, Cumans, Alans and (following the Battle of Manzikert) Turks meeting the Empire's appetite for light cavalry mercenaries. Since much of the Byzantine military focused on the strategy and skill of generals utilizing militia troops, heavy infantry were recruited from Frankish and later Varangian mercenaries.

From the seventh to the 12th centuries, the Byzantine army was among the most powerful and effective military forces - neither Middle Ages Europe nor (following its early successes) the fracturing Caliphate could match the strategies and the efficiency of the Byzantine army. Restricted to a largely defensive role in the 7th to mid-9th centuries, the Byzantines developed the theme-system to counter the more powerful Caliphate. From the mid-9th century, however, they gradually went on the offensive, culminating in the great conquests of the 10th century under a series of soldier-emperors such as Nikephoros II Phokas, John Tzimiskes and Basil II. The army they led was less reliant on the militia of the themes; it was by now a largely professional force, with a strong and well-drilled infantry at its core and augmented by a revived heavy cavalry arm. With one of the most powerful economies in the world at the time, the Empire had the resources to put to the field a powerful host when needed, in order to reclaim its long-lost territories.

After the collapse of the theme-system in the 11th century, the Byzantines grew increasingly reliant on professional Tagmata troops, including ever-increasing numbers of foreign mercenaries. The Komnenian emperors made great efforts to re-establish a native army, instituting the pronoia system of land grants in exchange for military service. Nevertheless, mercenaries remained a staple feature of late Byzantine armies since the loss of Asia Minor reduced the Empire's recruiting-ground, while the abuse of the pronoia grants led to a progressive feudalism in the Empire. The Komnenian successes were undone by the subsequent Angeloi dynasty, leading to the dissolution of the Empire at the hands of the Fourth Crusade in 1204.

The Emperors of Nicaea managed to form a small but effective force using the same structure of light and heavily armed troops, both natives and foreigners. It proved effective in defending what remained of Byzantine Anatolia and reclaiming much of the Balkans and even Constantinople itself in 1261. Another period of neglect of the military followed in the reign of Andronikos II Palaiologos, which allowed Anatolia to fall prey to an emerging power, the Ottoman emirate. Successive civil wars in the 14th century further sapped the Empire's strength and destroyed any remaining chance of recovery, while the weakening of central authority and the devolution of power to provincial leaders meant that the Byzantine army was now composed of a collection of militias, personal entourages and mercenary detachments.^[2]

History[link]

Just as what we today label the Byzantine Empire was in reality and to contemporaries a continuation of the Roman Empire, so the Byzantine army was an outgrowth of the Late Roman structure, which largely survived until the mid-7th century. The official language of the army for centuries continued to be Latin but this would eventually give way to Greek as in the rest of the Empire, though Latin military terminology would still be used throughout its history.

In the period after the Muslim conquests, which saw the loss of Syria and Egypt, the remainders of the provincial armies were withdrawn and settled in Asia Minor, initiating the thematic system. Despite this unprecedented disaster, the internal structures of the army remained much the same, and there is a remarkable continuity in tactics and doctrine between the 6th and 11th centuries. The Battle of Manzikert in 1071 and the subsequent Seljuk invasions, together with the arrival of the Crusades and the incursions of the Normans, would severely weaken the Byzantine state and its military, which increasingly had to rely on foreign mercenaries.

The army under Diocletian and Constantine[link]

Emperor Constantine I.

The Eastern Empire dates from the creation of the Tetrarchy ("Quadrumvirate") by the Emperor Diocletian in 293. His plans for succession did not outlive his lifetime, but his reorganization of the army did by centuries. Rather than maintain the traditional infantry-heavy legions,^{[citation needed]} Diocletian reformed it into limitanei ("border") and comitatenses ("field") units. There was an expansion of the importance of the cavalry, though the infantry still remained the major component of the Roman armies, in contrast to common belief. For example, in 478, an Eastern field army consisted of 8,000 cavalry and 30,000 infantry^{[citation needed]} and it can be calculated that in 357 Emperor Julian had 10,000 infantry and 3,000 cavalry at Strasbourg.^{[citation needed]} But the importance of cavalry for the commanding officers, though not the numbers, did increase, and by the time of Justinian, the numbers had increased, too.^{[citation needed]}

The limitanei and ripenses were to occupy the limes, the Roman border fortifications. The field units, by contrast, were to stay well behind the border and move quickly where they were needed, whether for offensive or defensive roles, as well as forming an army against usurpers. The field units were held to high standards and took precedence over Limitanei in pay and provisions.

Cavalry formed about one-third of the units, but as a result of smaller units, about one-quarter of the Roman armies consisted of cavalry. About half the cavalry consisted of heavy cavalry (including the stablesiani).^{[citation needed]} They were armed with spear or lance and sword and armored in mail. Some had bows, but they were meant for supporting the charge instead of independent skirmishing.^{[citation needed]} In the field armies there was a component of some 15% of cataphractarii or clibanarii, heavily armoured cavalry who used shock tactics. The light cavalry (including the scutarii and promoti) featured high amongst the limitanei, being very useful troops on patrol. They included horse archers (Equites Sagittarii). The infantry of the comitatenses was organized in regiments (variously named legiones, auxilia or just numeri) of about 500-1,200 men. They were still the heavy infantry of old, with a spear or sword, shield, body armour and a helmet. But now each regiment was supported by a detachment of archers and some skirmishers.^{[citation needed]} If needed, the infantry could take off (some of) their armour to act in a more flexible way as Modares did (according to Zosimus) during the Gothic War of the 370s.^{[citation needed]} The regiments were commanded by a tribunus ("tribune") and brigaded in pairs^{[citation needed]} (cavalry units did, too) under a comes. These brigades probably were tactical and strategic units only, as no traces survive of brigade staff corps.

On the other hand, little is known of the limitanei. The old legions, cohorts and cavalry alae survived there, and newer units were created (the new legions, or auxilia and vexillationes, amongst the cavalry. The limitanei infantry may have been lighter-equipped than the comitatenses infantry, but there is no evidence whatsoever. They were paid less than the field troops and recruited locally. Consequently, they were of inferior quality. However, they were in the line of fire. They countered most incursions and raids. Thus, it can be assumed they did have superior field experience (except in periods of long campaigning for the comitatenses), though that experience did not extend to large battles and sieges.

The Scholae Palatinae units, which were more properly known as the Schola Protectores Domestici and the "Protective Association of the Royal Escort" (also called the Obsequium), were the personal guard of the Emperor, and were created to replace the Praetorian Guard disbanded by Constantine I.

The legions in the third and fourth century were not the legions of the Republic or earlier Roman empire, that they consisted largely or solely of equites troops,^{[citation needed]} and that they tended to be far short of the Augustinian legion component of 5,000 men.

The Army of Justinian I and his successors[link]

This section requires expansion.

The following is drawn mainly from J.B. Bury's History of the Later Roman Empire: From the Death of Theodosius I to the Death of Justinian I (London, 1923; Dover Publications reprint, 1958).

The army of Justinian I was the result of fifth-century reorganizations to meet growing threats to the empire, the most serious from the expanding Persian empire. Gone were the familiar legions, cohorts and alae of old Rome, and in their place were small infantry battalions or horse regiments called a tagma or numerus. A tagma had between 300 and 400 men and was commanded by a tribune. Two or more tagmata formed a brigade, or moira; two or more brigades a division, or meros.

There were six classifications of troops.

1. The guard troops stationed in the capital.
2. The comitatenses of the old Roman field armies. In Justinian's day these were more commonly called stratiotai. Regular soldiers of the Roman army, the stratiotai were chiefly recruited from subjects of the empire in the highlands of Thrace, Illyricum and Isauria.
3. The limitanei. The least changed element of the Roman army, limitanei still performed their traditional duties of guarding frontiers and garrisoning border posts.
4. The foederati. They were a relatively new element in the army, recruited from the fifth century onwards from barbarian volunteers. They were formed into cavalry units under Roman officers. A ban on enlistments by Roman subjects was lifted in the sixth century, and their composition became mixed.
5. The Allies. These were bands of barbarians, Huns, Herules, Goths or others who were bound by treaty to provide the empire with military units commanded by their own chiefs, in return for land or yearly subsidy.
6. The bucellarii. The private armed retainers of generals, Praetorian Prefects, officers of lesser rank and the rich, the bucellarii were often a significant portion of a field army's cavalry force. The size of a retinue of bucellarii depended on the wealth of the employer. Their rank and file were called hypaspistai, or shield-bearers, and their officers, doryphoroi or spear-bearers. Doryphoroi took solemn oaths of fidelity to their patron and of loyalty to the emperor. One of most noted generals of the period, Belisarius, had been a doryphoros in Justinian's retinue before his becoming emperor. The bucellarii were usually mounted troops, mostly Huns, Goths and mountaineers of Thrace or Asia Minor.

Modern scholars estimate the total strength of the imperial army under Justinian to be between 300,000 and 350,000 soldiers.^[3] Field armies generally had 15,000 to 25,000 soldiers and were formed mainly of comitatenses and foederati, reinforced by the commanders' retinues and barbarian allies. The expeditionary force of Belisarius during his reconquest of Carthage from the Vandals in 533 is illustrative.

This army had 10,000 comitatenses and foederati infantry, with 3,000 similarly composed cavalry. There were 600 Huns and 400 Herules, all mounted archers, and 1,400 or 1,500 mounted bucellarii of Belisarius' retinue. The small force of less than 16,000 men voyaged from the Bospherus to North Africa on 500 ships protected by 92 dromons, or war-ships.

Tactics, organization and equipment had been largely modified to deal with the Persians. The Romans adopted elaborate defensive armor from Persia, coats of mail, cuirasses, casques and greaves of steel for tagma of elite heavy cavalrymen called cataphractii, who were armed with bow and arrows as well as sword and lance.

Large numbers of light infantry were equipped with the bow, to support the heavy infantry, called scutarii. These wore a steel helmet and a coat of mail, and carried a spear, axe and dagger. They generally held the center of a Roman line of battle. Infantry armed with javelins were used for operations in mountain regions.

Notable military events during the reign of Justinian included the battle of Daras in 530, when Belisarius, with a force of 25,000, defeated the Persian emperor's army of 40,000. In addition to his reconquest of Carthage, noted above, Belisarius also recaptured Sicily, Naples, Rome and the rest of Italy from the Goths in a war lasting from 536 to 540. Another famous commander of the time was the imperial eunuch Narses, who defeated a Gothic army at Busta Gallorum on the eastern coast of Italy in 552.

The armies of the middle Byzantine period, 7th-11th centuries[link]

[edit] The Themata

The themata (Gr. θέματα) were administrative divisions of the empire in which a general (Gr. στρατηγός, strategos) exercised both civilian and military jurisdiction and a Judge (Κριτής του Θέματος, Krites tou thematos) held the judicial power. The name is peculiar; Treadgold's closest guess is that thema was being used to denote "emplacements". Modern historians agree that the designations of the first themes came from the field armies that where stationed in Asia Minor.

The five original themata were all in Asia Minor and originated from the earlier mobile field armies. They were:

• the Armeniac Theme (Θέμα Άρμενιάκων, Thema Armeniakōn), first mentioned in 667, was the successor of the Army of Armenia. It occupied the old areas of the Pontus, Armenia Minor and northern Cappadocia, with its capital at Amasea
• the Anatolic Theme (Θέμα Άνατολικῶν, Thema Anatolikōn), first mentioned in 669, was the successor of the Army of the East (Άνατολῆ). It covered central Asia Minor, and its capital was Amorium.
• the Opsician Theme (Θέμα Ὀψικίου, Thema Opsikiou), first mentioned in 680, was where the imperial retinue (in Latin Obsequium), was established. It covered northwestern Asia Minor (Bithynia, Paphlagonia and parts of Galatia), and was based at Nicaea. Its commander bore the title of komēs ("count")
• the Thracesian Theme (Θέμα Θρακησίων, Thema Thrakēsiōn), first mentioned in 680, was the successor of the Army of Thrace. It covered the central western coast of Asia Minor (Ionia, Lydia and Caria), with capital at Ephesos.
• the corps of the Carabisiani (Kαραβησιάνοι, Karabēsianoi), first mentioned in 680, probably formed from the remnants of the Army of the Illyricum or the old quaestura exercitus. It occupied the southern coast of Asia Minor and the Aegean Islands, with its capital at Attaleia. It was a naval corps (κάραβις means "ship"), and its commander bore the title of droungarios. It was replaced with the Cibyrrhaeot Theme in the early 8th century.

Within each theme, eligible men were given grants of land to support their families and to equip themselves. Following revolts strengthened by the large size of these divisions, Leo III the Isaurian, Theophilus, and Leo VI the Wise all responded by breaking the themes up into smaller areas and dividing control over the armies within each theme into various tourmai. The large early themes were progressively split up in the 8th-9th centuries to reduce their governors' power, while in the 10th century, new and much smaller themes, called "Armenian themes" because many were settled by Armenians, were created in the East in conquered territories. While in ca. 842 the Taktikon Uspensky lists 18 strategoi of themes, the De Thematibus of ca. 940 lists 28, and the Escorial Taktikon, written ca. 971-975, lists almost 90 strategoi of themes and other military commands.^[4]

Sicily had been completely lost to the expanding Emirate of Sicily at the beginning of Constantine VII's reign in 905 and Cyprus was a condominium jointly administered with the Abbasid Caliphate until its reconquest by Nikephoros II Phokas in 965. Constantinople itself was under an Eparch and protected by the numerous tagmata and police forces.

Under the direction of the thematic strategoi, tourmarchai commanded from two up to four divisions of soldiers and territory, called tourmai. Under them, the droungarioi headed subdivisions called droungoi, each with a thousand soldiers. On the field, these units would be further divided into banda with a nominal strength of 300 men, although at times reduced to little more than 50. Again, the fear of empowering effective revolts was largely behind these subdivisions.

The following table illustrates the thematic structure as found in the Thracesian Theme, circa 902-936.