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The Byzantine Army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine Navy. A direct descendant of the legions of the old Roman Empire, the Byzantine Army maintained a similar level of discipline, strategic prowess and organization. For much of its history in fact, the Byzantine Army was the most powerful and effective military force in all of Europe.

The Army of the Eastern Roman Empire

Just as the Byzantine Empire (Gr. [Βυζαντινη Αυτοκρατορια] or, more properly, Βασιλεια Ρωμανιον) was a continuation of the Roman Empire, so the Byzantine army was an outgrowth of the earlier Roman structure. Provinces ('provinciae') were originally under civilian jurisdiction, with governors appointed by the Roman Senatus or by the emperor himself; the army consisted of thirty-odd legions quartered along the inhabited borders of the empire (See List of Roman legions).

The System of Diocletian and Constantine

The Eastern Empire dates from the creation of the Tetrarchy ('Quadrumvirate') by the emperor Diocletianus in AD 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, Diocletian reformed it into border and field units. As with all other forces during the middle ages, there was a loss of prestige and interest in the infantry and a corresponding expansion of the importance of the cavalry. This was assisted by the introduction and development of the saddle and the stirrup in the early Dark Ages and by the development of horses on the Iranian plateau sturdy enough to carry a man in full armor.

The border ('limitanei') units were to occupy the 'limes', the Roman border fortifications, and consisted of poorly-trained professional soldiers. 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. Field units were created by retooling the legions into cavalry units and maintained as small elite cadres with expensive training and weaponry. They consisted of:

Scholae units - properly the Schola Protectores Domestici, the "Protective Association of the Royal Escort" (also called the 'Obsequium,') the personal guard of the Emperor, created to replace the Praetorian Guard disbanded by Constantine I;
Palatinae units – the "Palace" units, the next highest ranked units;
Comitatenses' units – the "Line" or "Regular" units, some formed from the old legions, some new;
Pseudocomitatenses units – the "Irregular" units, some 'limitanei' units diverted into the field army, some the less-qualified former legions.

The legions still called as such in the third and fourth century consisted of:

Legiones I

Armeniaca – the "Armenian," 'pseudocomitatensis' under the command of the 'Magister militum per Orientis'
Flavia Constantia – the "Steady Flavian," 'comitatensis'
Flavia Gallicana Constantia – the "Steady Gaulic Flavian," 'pseudocomitatensis' under the command of the 'Magister Peditum'
Flavia Martis – the "Martial Flavian," 'pseudocomitatensis'
Flavia Pacis – the "Peaceful Flavian," 'comitatensis' under the Magister Peditum
Flavia Theodosiana – the "Theodosian Flavian," 'comitatensis'
Illyricorum - the "Illyrican"
Iovia - the "Jovian"
Isaura Sagitaria – the "Isaurian archers," 'pseudocomitatensis'
Iulia Alpina – the "Alpine Julian," an Italian 'pseudocomitatensis' under the Magister Peditum
Martia - the "Martial"
Maximiana Thaebanorum – the "Thebans' Maximinian," 'comitatensis'
Noricorum - "of the Noricans," from Styria
Pontica - the "Pontic," from the south-eastern coast of the Black Sea

Legiones II

Armeniaca – "Armenian" 'pseudocomitatensis'
Britannica – the "British," 'comitatensis' under the Magister Peditum
Flavia Constantia – 'comitatensis' under the Magister Peditum
Flavia Virtutis – the "Military Flavian." 'comitatensis' under the Magister Peditum
Herculia - the "Herculian"
Isaura - the "Isauran," from the Tarsus
Iulia Alpina – 'pseudocomitatensis' under the command of the Comes Illyricum
Felix Valentis Thebaeorum – "Valens' Lucky Thebans," 'comitatensis'
Legiones III
Diocletiana - the "Diocletian"
Flavia Salutis – the "Salvation Flavian," 'comitatensis' under the Magister Peditum
Herculea – 'comitatensis' under the Comes Illyricum
Isaura
Iulia Alpina – Italian 'comitatensis' under the Magister Peditum

Legiones IIII

Italica - the "Italian"
Martia
Parthica - the "Parthian," from the Persia marchland

Legiones V

Iovia
Parthica

Legiones VI

Gemina - the "Twin"
Gallicana - the "Gaul"
Herculia
Hispana - the "Spanish"
Parthica

Legio XII

Victrix - the "Victors"

(Source: Notitia Dignitatum)

Again note, however, that these were not the legions of the Republic or earlier Roman empire, that they consisted largely or solely of equites troops, and that they tended to be far short of the Augustinian legion component of 5,000 men.

The Armies of Justinian and his Successors

The Armies of the Middle Byzantine Period

The Themata

Established either by Heraklios or his successor Konstas II on the model of the Italian and African exarchates, the themes (Gr. θημ&alpha -τα) were administrative divisions of the empire in which a general (Gr. στρατηγος*) exercised both civilian and military jurisdiction. The name is peculiar; Treadgold's closest guess is that thema was being used to denote "emplacements."

The five original themata were all in Asia Minor and designed to counter the Arab 'jihad' that had already consumed the Egyptian and Syrian provinces. They were:

Thema Armeniakon, formed around the Army of Armenia established by Iustinianus, comprising eastern Anatolia from Kappadokia to the Black Sea and the Euphrates;
Thema Anatolikon, formed around the Army of the East, comprising the Byzantine holdings in central and south-eastern Asia Minor;
Thema Opsikion, formed around the 'Obsequium' (L. "Retinue"), a 'comitatensis' force previously kept in the presence of the emperor, comprising Bithynia and Paphlagonia;
Thema Thrakesion, formed around the Army of Thrace, comprising south-western Asia Minor around Ionia; and
Thema Karabisianon, the "Theme of Ships" in Pamphylia and Rhodos, which was a naval theme responsible for fending off the Arab navy.

Within each theme, eligible men were given grants of land to support their families and to equip themselves (πρωνοια). The population of the first four were directed into the army; Karabisianon supplied the men for the navy, although shipbuilding itself was subsidized (intermittantly) by various departments of the Imperial treasury. The pattern was adopted in short order for the Empire's holdings in the West as well.

Following revolts strengthened by the large size of these divisions, Leon III, Theophilos, and Leon VI all responded by breaking the themes up into smaller areas and dividing control over the armies within each theme into various tourmai. Further, instead of expanding existing themes, the emperors of the resurgent Macedonian dynasty tended to create new ones in the areas they conquered. By the time of the writing of De Thematibus in the tenth century, Konstantinos VII Porphyrogenes listed twenty-eight themata:

In Asia:

Thema Anatolikon, including parts of Phrygia, Lykaonia, Isauria, Pamphylia and Pisidia;
Thema Armeniakon, including parts of Armenia, Khaldia, and Kappadokia;
Thema Thrakesion, established by Leo III in Phrygia, Lydia and Ionia and named after the Thracian troops rotated there;
Thema Opsikion, including Mysia and part of Bithynia and Phrygia;
Thema Optimaton, named after the tagma ton Optimaton ('"Regiment of the Best"') stationed there, formed out of Opsiakian Bithynia;
Thema Bukellarion, named after the tagma ton Bukellarion ('"Regiment of the Companions"') stationed there, formed out of Opsiakian Galatia;
Thema Paphlagonias;
Thema Khaldias, the country about Trebizond and formerly called Pontos after the Black Sea (Gr. Ευξεινοσ Ποντοσ);
Thema Mesopotamias, the trifling possessions of the empire on the Mesopotamian frontier;
Thema Koloneias, the country between Pontos and Armenia Minor, through which the Lycus flows, near Neokaisareia;
Thema Sebasteias, consisting of the rest of Armenia;
Thema Lykandon, a theme formed by Leon VI the Wiss on the borders of Armenia;
Thema Kibyrraioton, the naval theme established by Leo III in Karia, Lykia, Rhodos, and the coast of Kilikia that replaced the earlier Thema Karabisianon;
Thema Kypriakon, the naval theme for Cyprus; and
Thema Aigiaon Pelagon, the naval theme for the Aegean.

In Europe:

Thema Thrakes, the area around but not including Konstantinoupolis;
Thema Makedonikon, the area around but not including Thessaloniki;
Thema Strymonos;
Thema Thessalonikes, the second city of the Empire;
Thema Helladikon, created between 687 and 695, consisted of Greece between Makedonia and the Isthmus, the former regions of Attica, Boeotia, Akarnania, and Aetolia;
Thema Peloponneson;
Thema Kephallenias;
Thema Nikopolitikon;
Thema Dyrrakhion, on the shore of modern Albania;
Thema Sikelias, a naval theme;
Thema Longibardias (also called Kalabrias) in Italy; and
Thema Khersonos (also called Thema ta Klimata) in the Crimea.

Note that this is a traditional list - Sicily had been completely lost to the Arabs at the beginning of Konstantinos's reign in 905 and Cyprus was a condominium jointly administered with the Muslim khalifa until its reconquest by Nikephoros II Phokas in 965. Konstantinoupolis itself was under an eparkhos and protected by the numerous tagmata and police forces.

Under the direction of the thematic strategoi, 'tourmarchai' commanded two from 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 (cf. Treadgold.)

The Imperial Tagmata

The Tagmata (ταγματα, "Regiments") were the standing army of the Empire, typically headquartered in or around Constantinople. The remains of Diocletianus's armies became the first tagmata, who were turned into the thematic forces under the Heraclids. Around the same time, some tagmata were formed as social clubs for the well-connected (δυνατοι) of the capital. Iustinianus, for instance, is said to have amused himself by including one of these units, the 'Scholae', in mock active deployment lists, thus causing a panic amongst their upper class gentlemen-soldiers, who had no desire to leave the safety of Constantinople for the discomfort and danger of an actual military campaign.

After the first set of thematic revolts reminded the emperors of the utility of a loyal standing force, however, the tagmata were reformed under a separate adminstration, improved in equipment and training, and continued to be used until the end of the empire.

The four most prestigious tagmata, in order, were

the Skholai (Gr. Σχολαι, the "Schools"),
the Exkoubitoi (Gr. Εξκουβιτοι, the "Watchmen");
the Arithmoi (Gr. Αριθμοι, the "Numbers") or Vigla (Gr. υιγλα, the "Watch"); and
the tagma ton Hikanaton (Gr. Ικανατοι, the "Worthies").

All of these were cavalry units consisting of from 1-6,000 men each. A strength of 4,000 each appears to have been standard. The Numeroi (Gr. Νουμηροι, "Bathhouse boys" for their base of operations in the city), the tagma ton Optimaton (Gr. Οπτιματοι, the "Best"), and the tagma ton Teikheon (Gr. Τειχεον, the "Wall") were infantry tagmata. The Vigla and the Numeroi assisted in the policing of Constantinople; the tagma ton Teikheon, as the name suggests, manned the Theodosian walls and was generally responsible for the defense of the capital.

In addition to these more or less stable units, any number of shorter-lived tagmata were formed as pet units of various emperors. Mikhael II raised the Tessarakontarioi, a special marine unit, and Ioannes Tzimiskes created a corps called the Athanatoi (the "Immortals") after the old Persian unit.

Foreign and Mercenary Soldiers

Foreign troops during the late Empire were known as the Foederati ("Allies") and continued to be known as such until about the ninth century (although the title had by then been Hellenized to Phoideratoi (Gr. Φοιδεράτοι). From this point, foreign troops (mainly mercenaries) were known as the Hetaireiai(Gr. Εταιρείαι, "Companions") and most frequently employed in the Imperial Guard. This force was in turn divided into the Great Companions (Μεγάλη Εταιρεία), the Middle Companions (Μέση Εταιρεία), and the Minor Companions (Μικρά Εταιρεία), commanded by their respective Hetaireiarches. These may have been divided upon a religious basis separating the Christian subjects, Christian foreigners, and non-Christians, respectively. (Source: The Book of Ceremonies by Konstantinos Porphyrogenitos)

Additionally, during the Comnenian period, the mercenary units would simply be divided by ethnicity and called after their native lands: the Inglinoi (Englishmen), the Phragkoi (Franks), the Skythikoi (Scythians), the Latinikoi (Latins), and so on. Ethiopians even served during the reign of Theophilos. These mercenary units, especially the Skythikoi, were also often used as a police force in Constantinople.

But, of course, the most famous of all Byzantine regiments was the legendary Varangian Guard. This unit traced its roots to the 6,000 Rus sent to Emperor Basil II by Vladimir of Kiev in 988. The tremendous fighting abilities of these axe-wielding, barbarian Northerners and their perceived loyalty (bought with much gold) established them as an elite body, and indeed, rose to become the Emperors’ personal bodyguard. This is further exemplified by the title of their commander, Akolouthos (Ακόλουθος, “Acolyte” to the Emperor). Initially the Varangians were mostly of Rus origin, but later many Scandinavians and Anglo-Saxons (after the Norman Conquest) entered the Guard. The Varangian Guard is thought to have been disbanded after the sack of Constantinople by the forces of the Fourth Crusade in 1204.

The Comnenian army

A powerful new force

Under Alexius, John and Manuel Comnenus, the power of the Byzantine Empire was restored by a new professional army, which was largely composed of Byzantine citizens and powerful mercenaries. It contained formidable guards units such as the Varangian Guard and the 'Immortals' (a unit of heavy cavalry) stationed in Constantinople, and also levies from the provinces. These levies included Kataphraktoi cavalry from Macedonia, Thessaly and Thrace, and various other provincial forces such as Trebizond Archers from the Black Sea coast of Asia Minor. Under John II, a Macedonian division was maintained, and new native Byzantine troops were recruited from the provinces. Soldiers were also drawn from defeated peoples, such as the Pechenegs, who fought as cavalry archers. Native troops were organised into regular units and stationed in both the Asian and European provinces. Units of archers, infantry and cavalry were grouped together so as to provide combined arms support to each other. This Comnenian army was a highly effective, well-trained and well-equipped force, capable of campaigning in Egypt, Hungary, Italy and Palestine. However, like many aspects of the Byzantine state under the Comneni, its biggest weakness was that it relied on a powerful and competant ruler to direct and maintain its operations. While Alexius, John and Manuel ruled (c.1081 to c.1180), this was not a problem. Yet, as we shall see, at the end of the twelfth century this competant leadership largely disappeared. The consequences of this breakdown in command were to prove disastrous for the Byzantine Empire.

The limitations of the twelfth century army

The decline of the 'theme' system, which had supplied large numbers of troops for the empire in earlier centuries, may have been an important factor in the eventual collapse of the empire. It is thought that the Byzantine field army under Manuel Comnenus (1143-1180) numbered some 40,000 men. Comparison with the thematic army that had existed in the ninth century shows that, at least on paper, considerably more men had been available for duty under the theme system. And like the late Roman army, the late Byzantine army was more costly than its earlier counterpart (although still less expensive than the large standing army of Basil II).

Although the role of mercenaries in the Byzantine army has been the subject of much debate, it is a common misconception that they formed the entire Byzantine army in this period. In fact, as we have seen, the Comneni emperors made significant efforts to recruit native units as well as mercenaries. Nevertheless, there is no doubt that mercenaries and auxiliary units provided by subject states did make up a substantial part of the army (perhaps one-third). Yet some mercenary units could be expensive. One of the advantages of the theme system was that it provided a means of mobilising large numbers of men cheaply. The collapse of the theme system, therefore, appears to have reduced the number of soldiers that the empire could afford.

Another advantage of the theme system may have been its simplicity. However, mobilising the Comnenian army of the twelfth century was a more complex affair, involving the raising of provincial levies, the mobilisation of guards units from the capital, divisions from the provinces, and summoning troops from subject states. This is not to say that the Comnenian army was any less effective (the thematic army's success rate was just as varied as that of its Comnenian counterpart); it is more the case that, although formidable under a competant leader, the twelfth century army was unable to protect the empire on its own. When incompetant or disinterested emperors took power, the Comnenian army was effectively leaderless.

It is even possible to argue that, with the demise of the theme system, one of the main strengths of the Byzantine state had been lost, and that therefore it is perhaps unsurprising that the empire disintegrated soon after the death of Manuel Comnenus. It was not the army itself that was to blame, but rather the system that supported it. Byzantium had come to rely too much on individual emperors. Without strong underlying institutions that would always be there, whether the emperor was good or bad, the state was extremely vulnerable in times of crisis.

The Armies of the Realms-in-Exile

Byzantine Army under the Paleologi

Byzantine Military History

Despite the importance the Byzantine Empire (or Ρωμανία, as it called itself) attached to its position as the defender of true, orthodox Christianity against Muslim and Catholic alike, it is worth noting that the Empire never developed or understood the concept of a "holy war." Its neighbours' concepts of Jihad and Crusade seemed to it gross perversions of scripture or simple excuses for looting and destruction. Emperors, generals and military theorists alike found war to be a failing of governance and political relations, to be avoided whenever possible. Only wars waged defensively or to avenge a wrong could in any sense be considered just, and in such cases the Byzantines felt that God would protect them.

Despite the importance the Byzantine Empire (or Ρωμαναι, as it called itself) attached to its position as the defender of true, orthodox Christianity against Muslim and Catholic alike, it is worth noting that the Empire never developed or understood the concept of "Holy War." Its neighbors' concepts of Jihad and Crusade seemed to it gross perversions of scripture or simple excuses for looting and destruction. Emperors, generals and military theorists alike found war to be a failing of governance and political relations, to be avoided whenever possible. Only wars waged defensively or to avenge a wrong could in any sense be considered just, and in such cases the Byzantines felt that God would protect them.

Sources

Notitia Dignitatum
A History of the Byzantine State and Society by Warren Treadgold
Warfare in Roman Europe by Hugh Elton
The Late Byzantine Army by Mark C. Bartusis
By John Haldon:
- Byzantium at War
- Warfare, state and society in the Byzantine World
- Byzantine Praetorians
The Idea of Holy War in the Orthodox World by Irina Moroz, from Quaestiones medii aevi novae v. 4