By Pat Lowinger
By the time of Muhammad’s death in 632 CE, the armies of Islam had already consolidated their control of the vast territories of the Arabian Peninsula. It was from these strongholds in Arabia that the first Rashidun Caliph, Abu Bakr, began several well-organized and coordinated military campaigns against the war-weary Byzantine and Sassanid empires. In 634 CE the Arabs launched a devastating military campaign into Roman Syria. The success of the Arabs against the Byzantine Empire owes as much to their own discipline and flexibility as it does the repeated tactical and logistical failures of the Byzantines. There are multiple additional factors which ultimately led to the Byzantine defeat in Roman Syria: recurring plagues during the 6th century, depleted imperial coffers, inadequate recruitment and retention of seasoned troops, and the appointment of inexperienced military commanders.
The Plagues of the 6th Century
In the century prior to the Arab invasions of Syria, the populace of the Byzantine Empire had been devastated by several outbreaks of bubonic plague. The first and most well known of these plagues struck Constantinople in 541 CE. The Byzantine scholar Procopius recorded outbreaks in Egypt and Syria during the same year. Historian William Rosen, author of Justinian’s Flea: Plague, Empire and the Birth of Europe, estimates the plague killed nearly 5,000 people a day in Constantinople following the diseases’ initial outbreak until the plague subsided four months later. Rosen further estimates that 15-25% of the Empire’s population died as a result of the initial outbreak and subsequent resurgences of the disease during the 6th century CE. In Roman Syria, three additional outbreaks of the disease struck again in 568, 581 and 635 CE. While it is unknown how many Syrians died in these subsequent outbreaks, scientists have determined that the same bacterial strain responsible for the initial outbreak in 541 CE was also responsible for these subsequent outbreaks as well.
These plagues disrupted the economy, military and political structure of the Empire. The resulting shortage of able bodied agricultural workers led to a severe drop in grain production throughout the empire. The relative scarcity of grain was followed by a dramatic rise in its price that crippled the Empire’s predominantly agrarian economy. Military recruitment and readiness levels fell as an increased number of men remained on their farms rather than enlisting in the army. The 540s saw a marked decrease in tax revenues as increasing numbers of taxpayers became victims of the disease. As the plague continued, the coinage of the empire was repeatedly debased, which caused rampant inflation to occur. The Emperor Justinian I (482-565 CE) responded by increasing the tax obligations of the landed aristocracy, who in turn demanded increased rents from their tenant farmers. These increased economic burdens produced severe strains upon the patron-client system which ultimately led to political unrest in Constantinople and abroad. In order to secure the legal status of tenant farmers, Justinian enacted several pieces of legislation prohibiting the confiscation of farms owned by members of the military. With no legal recourse to remit their lost income, many aristocratic landowners began to openly commit tax evasion in direct opposition to the Emperors’ decrees.
The Byzantine-Sassanid War (602-628 CE)
The murder of the Byzantine Emperor Maurice in 602 CE not only brought political instability to the Empire, but also a renewed conflict with the Sassanid Empire. The first two decades of the war saw several Persian victories. It wasn’t until 610 CE that Heraclius seized the Byzantine throne for himself, ending the civil war. Heraclius then marshaled and reorganized existing regional forces. Heraclius’ initial counterattacks into Anatolia were defeated. These defeats further sapped the empire’s limited amounts of men and materials. By 618 CE the Sassanid’s and their allies had captured Armenia, Syria, the Levant, Egypt and eastern Anatolia. With little or no financial reserves, the Emperor sought financial support from the Patriarch of Constantinople. After having gained access to the wealthy coffers of the Eastern Church, Heraclius rebuilt his tattered army over the next four years.
In the spring of 622 CE, Heraclius led an army against the Persians and their allies in Armenia. After securing the western portion of Armenia, Heraclius reestablished the former border garrisons in the region. In the spring of 624 CE, Heraclius’ armies were again on the march and conquered eastern Armenia. This was followed by the unsuccessful siege of Constantinople in 626 by the Sassanids and their Avar allies. In 627 CE, Heraclius’ armies penetrated into the heart of the Persian Empire. At Nineveh, in September of 627 CE, the Byzantine forces surprised the Persian army and defeated it. Having defeated the only remaining army in Mesopotamia, the Byzantines plundered the region at will. Faced with the possible loss of his kingdom, Khosrau II accepted humiliating terms of ‘peace.’ The victorious Byzantines returned home only to find the provinces of Syria, the Levant, Egypt and Armenia ravaged and in disarray. Victory in Persia had not eased the economic issues of the empire. The imperial treasury remained at critically low levels as much of the wealth taken from the coffers of Persia had been used to pay the army. Many of the army’s veterans retired soon after returning home. With very little money to recruit new soldiers, the numbers of garrison troops fell dramatically.
Author’s Note: Part 2 will contain a complete list of all reference material.
 Arthur Goldschmidt and Lawrence Davidson, A Concise History of the Middle East. (Boulder, CO: Westview Press, 2010), 34-35.
 Ibid., 45-46.
 Cyril Mango, The Oxford History of Byzantium (Oxford: Oxford University Press, 2002), 49.
 William Rosen, Justinian’s Flea: The First Great Plague, and the End of the Roman Empire (New York, NY: Penguin Books, 2008), 16-18.
 William Rosen, Justinian’s Flea: The First Great Plague, and the End of the Roman Empire (New York, NY: Penguin Books, 2008), 41-47.
 Costas Tsiamis et al., “Earthquakes and Plague During Byzantine Times,” Acta Medico-Historica Adriatica 11 (2013): 57.
 Ibid., 58-59.
 Mango, Byzantium, 49.
 Ibid., 49-50.
 Georgije Ostrogorski, History of the Byzantine State (New Brunswich, NJ: Rutgers University Press, 1969), 76-77.
 Mango, Byzantium, 51.
 Ibid., 53.
 Theophanes, The Chronicle of Theophanes: An English Translation of Anni Mundi 6095-6305 (A.D. 602-813), trans. Harry Turtledove (Philadelphia: University of Pennsylvania Press, 1982), 8-9.
 Ostrogorski, History of the Byzantine State, 100.
 Ibid., 103-104.
 John F. Haldon, The Byzantine Wars (Gloucestershire: The History Press, 2008), 64-65.
 Ibid., 65.