The Byzantine army was one of the most powerful and effective military forces in the world from the 7th to the 12th centuries.
Beginning to operate around 395 AD, the Army of Byzantium was a continuation of the mighty Roman Army in the East, with the Commander-in-Chief being the Byzantine Emperor.
Subsequently, the Byzantine army followed the structure of the Roman army, known for its strict discipline, rigid organization, and skillful combat strategies.
The Byzantine Empire became one of the most important in history, connecting Greece, the Christian faith and Western Europe.
From the 7th to the mid-9th century, the role of the Byzantine army was primarily defensive due to the attacks – and territorial losses – suffered by the Muslim Rashidun caliphate.
The theme system
To counter the more powerful caliphate during this period, the Byzantine army adapted the “theme” system.
The theme (or thema, from the Greek word θέμα) was an administrative division of the empire in which a general exercised both civil and military jurisdiction and a judge held judicial power.
Byzantium had lost almost half of its territory during the attacks of the caliphate and between 659 and 662 its army accepted a truce with the caliphate and regrouped.
The original five themes (plural of thema) were all in Asia Minor, made up of earlier field armies. More specifically, they were:
The Armenian theme, successor to the army of Armenia which occupied the ancient regions of Pontus, Armenia Minor and northern Cappadocia, with its capital at Amasea.
The Anatolic Theme, the successor of the Army of the East (Ανατολή). It covered central Asia Minor and its capital was Amorium.
The Opsician theme was where the Imperial Suite (in Latin Obsequium) was established. It covered the northwest of Asia Minor (Bithynia, Paphlagonia and parts of Galatia) and was based in Nicaea.
The Thracian theme, the successor to the army of Thrace. It covered the central west coast of Asia Minor (Ionia, Lydia and Caria), with Ephesus as its capital.
The Carabisiani theme, probably formed from the remains of the army of Illyria or the ancient quaestura exercitus. It occupied the southern coast of Asia Minor and the islands of the Aegean Sea, with its capital at Attaleia.
The latter was the naval force of the empire, replaced by the Cibyrrhaeot theme at the beginning of the 8th century.
The imperial tagmata of the Byzantine army
Being far from Constantinople, the seat of the Empire, the themata were not as loyal to the emperor as they should be.
Emperor Constantine V formed a new force, the tagmata (“regiments”). They were made up of professional soldiers and they were the army of the Empire.
The tagmata were in fact the reformed units of the old guard of Constantinople, intended to provide the emperor with a strong force of loyal guards.
The reason for the formation of the tagmata was to suppress a major revolt in the Opsician theme in 741-743.
The Byzantine army is transformed in the 11th century
The rule of the Comnena dynasty which began in 1081 (until around 1185) found the Byzantine Empire at its weakest, having lost most of its former territories and plagued by civil wars.
Alexios I Komnenos, the first of the five emperors of the Comnena dynasty, was determined to stop the decline and revive the empire, reclaiming lost territories and expanding.
Komnenos’ priority was to completely restore the army. The thematic system was abandoned and new military priorities prevailed.
The new Comnenian army was formed with skilled guard units such as the Varangian Guard and the Immortals (a heavy cavalry unit) stationed in Constantinople.
There was also the mighty cataphractory cavalry from Macedonia, Thessaly and Thrace, and various other provincial forces from regions such as the Black Sea coast of Asia Minor.
A multi-ethnic army
The Byzantine army of the 11th century and on foreign mercenaries widely used.
The same practice was followed by the Greek states which emerged after the conquest of Constantinople by the Crusaders in 1204, such as the Empire of Nicaea or the Despotate of Epirus.
The mercenaries of the Byzantine army literally came from almost every nation in the then known world:
The Hungarians were part of the forces of Ioannis II Komnenos in his campaign against the Seljuks. Later, in the 13th century, Hungarian warriors participated in the army of the Empire of Nicaea.
The Latins, also known as the Franks, were predominantly French, while in much smaller numbers there were Italians, Spaniards, and Germans among them, serving primarily as heavily armored cavalry.
The Turks (Seljuks, Ottomans and others) have always been an important part of the armies of the Byzantine Empire, serving as mercenaries.
Catalans were used by the Byzantines from the 1270s until the 15th century. The most typical case of such troops was the so-called “Catalan Company”, which was hired by Andronikos II Paleologos to fight the Turks in 1302.
The Alanians, an Iranian nation from the Caucasus, were considered the best horsemen in the East. From the end of the 11th century to the beginning of the 14th century, they supplied the Byzantines with cavalry archers.
The Burgundians were also part of the mix. In 1445, the Duke of Burgundy sent 300 warriors to militarily reinforce the despotate of Morea against the Ottomans. In addition, many Burgundian mercenaries served the Byzantine emperors throughout the 15th century.
The Scandinavians were also present in the Byzantine army. The Varangian Guard was a selected mercenary unit of men from various nations of northern Europe. Their mission was to keep the emperor, to whom they were devoted until death.
It was a great honor for the Vikings to travel to Constantinople and serve in the Emperor’s bodyguard. It was a service that ensured fame as well as money.
The Saxons and the English first appeared as mercenaries in the Byzantine army in the 1080s. From the 12th century, they were classified in the Varangian Guard, as a nation in northern Europe.
In the 12th century, many Russian rulers provided the Byzantine army with infantry warriors, seeking to maintain friendly and allied relations with Constantinople. They were also classified in the Varangian guard.
At the battle of Pelagonia, in 1259, the Bulgarians had a remarkable action, as mercenaries in the army of Nicaea. Until the second half of the 14th century, they participated more and more in Byzantine forces.
Under the conditions imposed on the Serbs by Constantinople at the beginning of the 12th century, they were obliged to provide the emperor with 500 cavalry for operations in Anatolia.
In the 14th century, hundreds of Albanian mercenaries were part of the Byzantine forces in Thessaly and the Peloponnese. Their number rose to 10,000 in the 1390s.
Mercenaries from the Kingdom of Georgia sometimes served as cavalry divisions in the Byzantine army, mainly in the 12th century but also at the beginning of the 13th century.
Auxiliary corps of Armenian soldiers fought on behalf of the Byzantines in the 12th and 13th centuries. They have been used occasionally in northern Syria and Asia Minor.
The Empire of Nicaea used Mongolian auxiliary soldiers in its campaigns against the Seljuks, from 1220 to 1240. In 1282, 4000 warriors of Nogai Khan, participated in the army of Michael IX, during its operations against the Latins of Thessaly.