Byzantion (Greek: Βυζάντιον) was the name of a humble city located on the Bosporus, later called Byzantium by the Romans. It was founded by Dorian Greek colonists from Megara during the seventh century BC to secure Greek shipping routes to and from the Black Sea region. The city achieved some prominence as a trade hub during the zenith of the Roman Empire before being sacked by the forces of Septimius Severus in 195, as a result of having sided with the usurper Pescennius Niger during the Year of the Five Emperors (193). Although Septimius Severus recognised the city’s potential and rebuilt it, Byzantium was given a far greater destiny only in 330 when Constantine the Great (r. 306 – 337) chose the city as his new imperial residence and capital, a decision which altered the course of Roman and indeed European history.
Several factors influenced Constantine’s choice: Byzantium’s strategic position at the gateway between two continents, the increasing economic and demographic importance of the Roman Empire’s eastern territories and last but not least, Constantine’s desire to literally distance himself and his government from the less than cooperative senatorial elite back in Rome. Constantine and his son Constantius II (r. 337 – 361) did everything in their power to make Byzantium – soon renamed as Nova Roma Constantinopolitana or Constantinopolis – into a citadel with all the imperial grandeur of Rome in its heydays, combining the fledgling Christian architecture with the established Roman urban culture. At the death of Constantius II, the city’s governmental and ceremonial heart consisted mainly of the Great Palace (Greek: Μέγα Παλάτιον), the Hagia Eirene (Greek: Ἁγία Εἰρήνη), the Hippodrome (Greek: Ιππόδρομος) and the Forum of Constantine (Greek: Φόρος Κωνσταντίνου). On top of that, a new Byzantine Senate was established with its own Curia to emphasise Constantinople’s status as the New Rome, free from the corruption and conspiracies of the Roman senators in the west.
The continuous dedication of the Roman – Eastern Roman after the imperial division of 395 – government to the construction of Constantinople caused its population to skyrocket between the fourth and sixth century, in sharp contrast to the decline of Rome itself. Of the approximately 800,000 people living in Rome at the time of its infamous destruction by the Visigoths in 410, a mere 30,000 remained halfway through the sixth century. Constantinople had by this time become the greatest metropolis of the Mediterranean with around 500,000 inhabitants. Although the city’s population dwindled slightly over the next centuries and never outclassed the imperial zenith of Rome, Constantinople was undoubtedly the supreme jewel of medieval Europe until the forces of the Fourth Crusade desecrated the city in 1204.
The fall of the Western Roman Empire in 476 and the disappearance of its last splinter territories by 486 caused the imperial government of Constantinople to begin propagating a renovatio imperii, a restoration of the empire’s territory and authority. To Constantinople, the fall of the west meant before anything that there was finally a single Roman Empire again. Moreover, that the ‘inferior’ western barbarians had not only toppled Rome but also claimed its legacy was considered an unforgiveable insult. As the sole continuation of the empire, Constantinople considered itself the rightful ruler of all the former Roman territories in the west, a claim it considered both possible and inevitable.
The man who zealously pursued the renovatio-policy was Justinian the Great (r. 527 – 565). From the moment of his ascension to power, he embarked on an ambitious quest consisting of four objectives: the reconquest of the lost western territories, the purification and codification of Roman law, the establishment of religious unity and a military-first economy. Justinian’s multi-front wars, vast construction programs (most famously the Hagia Sophia in Constantinople) and heavy taxation pushed the empire and its people to the limit of their abilities. Despite considerable successes, the ultimate goal of restoring the Roman Empire proved unrealistic, all the more because difficulties turned into calamities as the sixth century progressed. The first plague epidemic hit the Mediterranean hard from 541 onward, the war against the Ostrogoths in Italy dragged into the 550’s and the Sassanid Empire reinitiated hostilities in the east from 542. In the north meanwhile, barbarian invasions breached the imperial frontier once more: the Avars and Bulgars entered the Danube Valley from the Ukraine, subjugating Slavic tribes along the way and forcing them to in turn invade the Balkans in search of a new home. In the west meanwhile, Constantinople’s hard-fought victories in Spain and Italy were all but undone by the Visigoths and Langobards, although the empire long held on to key Italian regions which included Rome and Ravenna. The catastrophes towards the end of Justinian’s reign and after his death in 565 proved to be merely the overture to the storms of the seventh century. The power of Constantinople nevertheless held out well enough at first: emperor Herakleios (r. 610 – 641) booked a spectacular victory at the Battle of Nineveh in 627 which shattered the Sassanid Empire, secured the imperial frontier in the east and allowed Constantinople to begin planning the reconquest of the Balkans against the Slavs.
Fate decided otherwise: less than a decade after Nineveh, the imperial armies were retreating in the face of the Arab tribes, recently united in the new faith of Islam. Shortly after Herakleios’ death in 641, Arab forces had secured the entire Middle East and went on to conquer Egypt by 642. These colossal demographic and territorial losses inflicted an unprecedented internal crisis upon Constantinople’s economy, military and administration. In response, Herakleios and his successor Constans II (r. 641 – 668) embarked on a campaign of sweeping reforms to suit the new situation and consolidate what was left of the empire. The result was the emergence of a ‘new’ Greco-Roman state, indeed the immediate continuation of the (Eastern) Roman Empire but one which had been thoroughly altered by decades of catastrophes and the rising significance of its Greek component. From around this time, the dominion of Constantinople is popularly known to modern-day people as the ‘Byzantine Empire’. However, both the government and the people stubbornly continued to call themselves and their empire ‘Roman’.
The reforms which shaped the emergence of the Byzantine state were nevertheless huge: the countryside of the empire was given a new taxation system which called for taxes in the form of gold alone and charged the local leaders of peasant communities with coordinating tax collection. The vital monetary link between the empire’s tax payers and government officials was thus preserved and strengthened. This was indeed of the greatest importance: the loss of inhabitants, resources and territory both required and implied a more efficient micro-management of the remaining territories. As a result, both the imperial army and bureaucracy shrunk significantly during the seventh and eighth century. Whereas Constantinople fielded an army as large as 150,000 soldiers in the days of Justinian the Great, it could count on ‘only’ 80,000 halfway through the eighth century. Likewise, the central government in Constantinople consisted of about 2,500 officials when Justinian came to power, as opposed to a mere 600 at the dawn of the eighth century.
In said situation of severe contraction, emperor Constans II also enforced a complete reorganisation of the Byzantine military around 660. It continued to be made up of semi-professional soldiers and enlistment remained voluntary, but its structure was rebuilt around four field armies: the themata (Greek: (pl.) θέματα), which were all stationed in the empire’s new heartland of Asia Minor. A fifth thema was soon established in the Aegean Sea to represent the Byzantine war fleets, followed by the creation of themata in the remaining Byzantine territories in the western Mediterranean. The new system was quickly expanded and enhanced under Constans II’s successors and ultimately became a new Byzantine administrative framework which replaced that of the Roman emperors Diocletian and Constantine.
To complement the themata, prevent a repeat of the Arab sieges of Constantinople (673 – 678 and 717 – 718) and more effectively combat the increasing number of internal conspiracies against the emperor, Constantine V (r. 741 – 755) created new units with only professional soldiers: the tagmata (Greek: (pl.) τάγματα), which in theory numbered altogether 18,000 men. Constantine V thus dramatically increased Constantinople’s defensive capacity and his own ability to crush internal threats to his power. However, the emperor’s position ultimately came at risk of being challenged or controlled by his own tagmata-commanders. To solve this, a new force was fielded in the tenth century to serve as the emperor’s personal bodyguard, one which largely consisted of Scandinavian soldiers: the famous Varangian Guards (Greek: Τάγμα των Βαράγγων). The downside to assembling the tagmata was the gradual decline in quality of the themata. Two main reasons can be brought up for this: firstly, the general preference of cavalrymen to serve in the tagmata rather than the themata, not in the least because the former paid better; secondly, the gradually increasing importance of cavalry-heavy armies. Already in the ninth century, the Byzantine military had to order peasant communities all over the empire to reserve a certain number of cavalrymen for service in the themata.
As the ninth century progressed, the internally reconsolidated Byzantine Empire could finally prepare its great war of reconquest. Byzantine forces had managed to reclaim the western Peloponnese shortly after 800 – killing or deporting the Slavs and repopulating the area with Greeks – but were hindered in further expansion by internal strife and strong foreign enemies, most notably the Bulgarian Empire. The fall of the Avar Khaganate by 804 had allowed for a remarkable rise in Bulgarian power and prosperity, establishing an empire which roughly encompassed modern-day Bulgaria, all of Macedonia and vast portions of modern-day Serbia, Greece and Albania. For centuries, the Byzantine emperors could do little more than to tolerate the Bulgarian khans, all the more because Constantinople’s Arab nemesis continued to terrorise the Mediterranean.
By the end of the ninth century, Byzantium achieved new successes by driving the Arabs out of Cilicia and strengthening its hold on southern Italy. The subsequent string of Byzantine victories which happened throughout the tenth and early eleventh centuries were the result of the internal weakening of the Arabs in the Middle East and the creation of political stability within the Byzantine government. A kind of balance of power had emerged between the hereditary monarchy of the emperor and the governmental influence of the Byzantine army, which implied that the Byzantine generals agreed to act reservedly in case of troubles within the monarchy but were allowed considerable influence over the seating emperor. Though said balance was indeed the fundament of the tenth century Byzantine successes, it turned the imperial court of Constantinople into a grand theatre of hypocrisy, flattery, factionalism and backstage conspiracies where one had to tread lightly to avoid disappearing from the stage at the command of either the regime or the military.
Two emperors defined the Byzantine tenth century: Constantine VII (r. 913 – 959) and his grandson Basil II (r. 963 – 1025). However, Constantine stood initially under the regency of the Patriarch of Constantinople, subsequently ruled alongside his mother Zoe Karbonopsina and then had to tolerate general Romanos Lekapenos as co-emperor until 944. His grandson Basil II ruled consecutively alongside his generals Phokas until 969 and Tzimiskes until 976.
The upside to the immense power of these generals was that the Byzantine armies could act decisively on every front, being commanded by men who had no real superior. Lekapenos turned the tables in the Balkans and increased Byzantine pressure on the Bulgarian Empire, which had reached the zenith of its power under khan Symeon (r. 893 – 927), even attempting a siege of Constantinople itself (923 – 924). Phokas reestablished firm Byzantine control over Cilicia, reclaimed Crete in 961 and Cyprus in 965, annexed Armenia and secured the gateway into Syria by reconquering Antioch in 969. Tzimiskes then initiated the annexation of Bulgarian Thrace, reduced the Mirdasids of Aleppo to a Byzantine vassal and invaded the Middle East, conquering key cities like Edessa, Tripoli, Sidon and Damascus but falling short of Jerusalem itself.
The downside to the Byzantine army’s state-influence became clear upon the death of Tzimiskes in 976: the empire fell into thirteen years of civil war before Basil II managed to regain control, greatly aided by a military alliance with Vladimir the Great of Kievan Russia. Once firmly in power, Basil II pushed the military policies of his late co-emperors to the limit. In 1014, Byzantium obliterated the Bulgarian army at the Battle of Kleidon and systematically conquered the Bulgarian Empire. By 1018, all remaining Bulgarian resistance had been destroyed. The ruthlessness of the Byzantine armies – even by medieval standards – gained Basil II the epitaph of ‘Bulgar Slayer’ (Greek: Βουλγαροκτόνος), by which he is known to this very day. Basil subsequently annexed significant territories in the Caucasus before turning west to strengthen Byzantine positions in southern Italy. Throughout his reign, Byzantium’s only military failure was the attempted invasion of Muslim Sicily.
The wars of reconquest waged by Basil II transformed the Byzantine armies along the general lines of military development going on in both the Latin West and the Islamic world. The importance of cavalry units increased dramatically: heavily armoured cavalrymen were given a more offensive role on the battlefield, whereas infantry units were trained to protect cavalry with carré formations. The new battle tactics stood side by side with a new system of military recruitment and maintenance. Basil II introduced the principal of subsidiary fiscal solidarity, which meant that rich land owners had to take over the fiscal duties (and not the land) of low-class peasants with financial difficulties. When lands fell to the tax collectors of the government, it was not sold but given in ‘lease’ to richer citizens which then had to pay for the armour, horses and wages of cavalrymen. As such, the Byzantine government both managed to maintain the army as a public institution to which all imperial citizens contributed and prevented – at least initially – that local or regional potentates gained too much power and could establish their own de facto autonomous dominions (which was the case all over the Latin West during the Early Middle Ages).
Approximately halfway through the eleventh century, the Byzantine Empire had once again become arguably the strongest state of the medieval Mediterranean world, having almost doubled its territory since the eighth century and ruling unopposed from the Straits of Messina to the Caucasus Mountains and the eastern shores of the Black Sea. However, the rapid expansion caused the iron grip of the imperial government to loosen under the rule of Zoe Porphyrogenita (r. 1028 – 1050) and her successive co-rulers (Romanos III, Michael IV, Michael V, her sister Theodora and Constantine IX), causing the powerful families of Asia Minor to gain significant local autonomy and act increasingly without orders from Constantinople…