3.6 Division and Decline

The relative political and religious unity Justinian’s campaigns brought back to Byzantium declined steadily after his death. For almost 1,000 years, the two kinds of Christianity – later called “Catholic” and “Eastern Orthodox,” although both terms speak to the idea of one universal and correct form of Christian doctrine – were sundered by the great political divisions between the Germanic kingdoms of the West and Byzantium itself in the East. In Eastern Europe, small kingdoms and poor farmers played host to rival missionaries preaching the slightly-different versions of Christianity. Trade existed, but was never as strong as it had been during the days of the united empire.

Byzantium’s major ongoing problem was that it faced a seemingly endless series of external threats. Byzantium was surrounded by hostile states and groups for most of its existence, and it slowly but steadily lost territory until it was little more than the city of Constantinople and its immediate territories. It is important to remember, however, that this process took many centuries, longer even than the Roman Empire itself had lasted in the West. During that time, Constantinople was one of the largest and most remarkable cities on the planet, with half a million people and trade goods and visitors from as far away as Scandinavia, Africa, and England. Its people believed that their empire and their emperor were preserved by God Himself as the rightful seat of the Christian religion. Thanks to the resilience of its people, the prosperity of its trade networks, and the leadership of its emperors, Byzantium remained a major state and culture for centuries despite its long-term decline in power from the days of Justinian.

The most significant leader after Justinian was the emperor Heraclius (r. 610 – 641). He was originally a governor who returned from his post in Africa to seize the throne from a rival in the midst of a Persian invasion. The Empire was in such disarray at the time that the Persians seized Syria, Lebanon, and Egypt, cutting off a huge part of the food supply to Constantinople. In the process, the Persians even seized the “True Cross,” (the cross on which it was believed Christ Himself had been crucified), from its resting place in Jerusalem. Simultaneously, the Avars and Bulgars, barbarian peoples related to the Huns, were pressing Byzantine territory from the north, and piracy was rife in the Mediterranean. Heraclius managed to save the core of the Empire, Anatolia and Greece, by recruiting free peasants to fight instead of relying on mercenaries. He also focused on Anatolia as the breadbasket of the Empire, temporarily abandoning Egypt but keeping his people fed. He led Byzantine armies to seize back Jerusalem and the True Cross from the Persians, soundly defeating them in 628, and in 630 he personally returned the True Cross to its shrine in Jerusalem. The fighting during this period was often desperate, but in the end Heraclius managed to pull the empire back from the brink.

Despite his success in staving off disaster, however, a new threat to Byzantium was growing in the south. The very same year that Heraclius returned the True Cross to Jerusalem, the Islamic Prophet Muhammad returned to his native city of Mecca in the Arabian Peninsula with the first army of Muslims. Heraclius had no way of knowing it, but Byzantium would soon face a threat even greater than that of the Persians: the Arab caliphates. Indeed, Heraclius himself was forced to lead Byzantium during the first wave of the Arab invasions, and despite his own leadership ability vital territories like Syria, Palestine, and Egypt were lost during his own lifetime (he died in 641, the same year that most of Egypt was conquered by the Arabs).

Organization

Heraclius created a new administrative system to try to defend the remaining Byzantine Territory. He began by seizing lands from wealthy landowners and monasteries in Asia Minor, then using the seized land as the basis for new territories from which to recruit soldiers. A theme was a territory, originally about a quarter of the empire in size, organized around military recruitment. A single general appointed directly by the emperor controlled each theme. In turn, only soldiers from that theme would serve in it; this led to local pride in the military prowess of the theme, which helped morale. It was only because of the success of the themes that Byzantine losses were not much worse, considering the strength of their foreign enemies.

Eventually, the themes changed further into self-sustaining military systems. Soldiers were granted land to become farmers. From there, they were to fund the purchase of weapons for themselves and their sons. Young men still joined the army, but the system could operate without significant cash-flow from the imperial treasury back in Constantinople. In essence, the theme system was a return to the ancient manner of military recruitment that had been so successful during the days of the Roman Republic: free citizens who provided their own arms, thereby relieving some of the financial burden on the state. At their height, the themes supported an army of 300,000 men – comparable to the Roman army under Augustus – with the financial burden evenly distributed across the empire.

The four themes were divided over the centuries, with villages being watched by commander and people fighting directly alongside their neighbors and families. Ultimately, it was this system, one that encouraged morale and loyalty, that preserved the empire for many centuries. One straightforward demonstration of the strength of the system was that the perennial enemy of Rome, the Persians, fell against the Arab invasion of the seventh century while the Byzantines did not.

There is an important caveat regarding the consideration of the themes, however. While Byzantium did indeed survive as a state for many centuries while neighboring empires like Persia fell, Byzantium itself arguably ceased to be an “empire” by the middle of the seventh century CE. The Arab invasions swiftly destroyed Byzantine power in the Near East and North Africa, and while fragments of Justinian’s reconquest remained in Byzantine hands until the eighth century, “Byzantium” was basically synonymous with the contiguous territory of the Balkans, Greece, and most of Anatolia by then. It was, despite its continued pretensions to empire, really a kingdom after the territorial losses, peopled almost entirely by Greek-speaking “Romans” rather than by those Romans as well as its former Syrian, Jewish, African, Italian, and Spanish subjects.

Imperial Control and Barbarians

Justinian’s successors tried to hold on to North Africa, Italy, and Spain by establishing territories called exarchates ruled by governors known as exarchs; exarchates were military provinces in which civilian and military control were united. They held out in Spain until the 630s, Africa until the end of the seventh century, and Italy until 751, when a Germanic tribe called the Lombards captured it. While the losses of territory in Europe were mourned by Byzantines at the time, they proved something of a blessing in disguise to the Empire: with its territory limited to the Balkans and Anatolia, the smaller empire had much more coherent and easily-defended borders. Thus, those core areas remained under Byzantine control despite various losses for many centuries to come. The emperor Leo the Isaurian (r. 717 – 741) used themes-recruited soldiers to both fight off Arab sieges of Constantinople and to cement control of Anatolia. By the end of his reign, Anatolia was secure from the Arabs and would remain the major part of the Byzantine Empire for centuries.

In addition to the themes system, the Empire added heavy cavalry to its roster and, famously, used a substance called Greek Fire in naval warfare; there are very few details, but it appears to have been an oil-based incendiary substance used to attack enemy ships. Finally, the empire made liberal use of spies and agents who infiltrated enemy governments and bribed or assassinated their targets to disrupt, or to start, wars.

In the Balkans, Slavic tribes proved a major ongoing problem for the Byzantines. A people known as the Avars invaded from the north in the sixth century and raided not just the Balkans but all across Europe, making it as far as the newly-created Frankish kingdom in present-day France. In the eighth century an even more ferocious nomadic people, the Bulgars invaded. While the Avars had converted to Christianity during the period of their invasions, the Bulgars remained pagan. They destroyed the remaining Byzantine cities in the northern Balkans, slaughtered or enslaved the inhabitants, and crushed Byzantine armies. In one especially colorful moment in Bulgarian history, the Bulgar Khan, Krum, converted the skull of a slain emperor into a goblet in about 810 CE to toast his victory over a Byzantine army. Fifty years later, however, another Khan, Boris I, converted to Christianity and opened diplomatic relations with Constantinople. This was an interesting and surprisingly common pattern: many “barbarian” peoples and kingdoms willingly converted to Christianity rather than having Christianity imposed on them through force. The Bulgars were consistently able to defeat Byzantine armies and they occupied territory seized from the Byzantine Empire, yet Boris I chose to convert and to insist that his followers do as well. The major reason for this deliberate conversion revolved around the desire on the part of barbarian kings to, simply, stop being barbarians. Most kings recognized that Christianity was a prerequisite to entering into trade and diplomatic relations with Byzantium and the Christian kingdoms of the West. Once a kingdom converted, it could consider itself a member of the network of civilized societies, carry out alliances and trade with other kingdoms, and receive official recognition from the emperor who still wielded considerable prestige and authority, even outside of the areas of direct Byzantine control.