Armstrong Undergraduate Journal of History

The Death Toll of Justinian’s Plague and Its Effects on the Byzantine Empire




Armstrong State University


The glory of the Roman Empire was a distant memory by the time the Byzantine Emperor Justinian (r. 527–565) came to power in 527. For Justinian too much time had passed since the western provinces had slipped from Roman control, and he set out to be the emperor to restore the glory to the mighty Roman Empire. In 533 Justinian secured the “endless peace” with the formidable Persian Empire in exchange for eleven thousand gold pounds annually.[1] By 540 the Byzantine military had made significant gains in North Africa and the Italian Peninsula.  However, in 541 a plague began in Constantinople and two years later ravaged the Byzantine Empire. The exact nature of the plague is unknown, although it is widely believed to be a strain of the Bubonic Plague.[2] The high mortality rate of the plague caused a severe shortage of labor that had a tremendously negative effect. The plague’s high virulence and subsequent strain placed on the empire both militarily and economically directly resulted in the decline of the Byzantine Empire.



Mosaic of Justinian, d.546
at San Vitale, Ravenna

Prior to 534, the Byzantine Empire’s military campaigns had been successful for a few years. In 534, Justinian dispatched future general Belisarius to reconquer Northern Africa. The final decisive battle between the Vandals and the Byzantine force was at Tricamarum, and Belisarius’s victory here effectively wiped the Vandals off the world’s stage. Justinian had now recaptured the Vandal kingdom; he was able to turn his attention to Italy. In 535 Belisarius began his march on Italy where he occupied Naples and Rome from the hands of Goths. After the newly chosen Gothic King Vitigis regrouped his army, he brought it against Rome. Belisarius withstood the siege of Rome, which lasted over a year.



The most important source of information during this time comes from the Byzantine Historian Procopius. He was present with Belisarius during most of his campaigns, and his work History of the Wars details the experience. Procopius tells of a letter sent by Belisarius in which he asks for reinforcements from Justinian: “... we have left an army of only five thousand. The enemy is coming against us to the number of one hundred fifty-thousand.”[3] While the enemy’s numbers were clearly exaggerated here the letter is demonstrative of a readiness of Justinian to provide reinforcements on a substantial scale. First an army of sixteen hundred cavalry arrived, and then later a much more formidable force arrived. The reinforcements are detailed by Procopius; “Three thousand Isaurians, eight hundred Thracian cavalry and one thousand regular cavalry, plus three hundred other cavalry under Zeno, who already reached Rome, and the five hundred from Campania.”[4] By 538 the siege of Rome was over and the Goths retreated to Ravenna. The Goths offered Belisarius the Kingship, which he quickly accepted and entered the city in 540. With this campaign over, Byzantium had reconquered a large portion of the Italian Peninsula. The most devastating event to occur to the empire, however, was still looming around the corner.


In 541 a plague arrived in Egypt and rapidly began to spread. The following account of the beginning of the plague, while clearly an exaggeration still shows the impact of the disease.  “At about this time a plague occurred, as result of which all human life was very nearly extinguished.”[5] Procopius details the early spread of the plague stating, “It began with the Egyptians who live in Pelusium. It divided and part went to Alexandria and the rest of Egypt, and part to the people of Palestine, the neighbors of the Egyptians, and from there overran the whole earth.”[6]  It arrived in Constantinople most likely from the port of Alexandria, and from there spread across Byzantium. “This disease always began from the coast and then moved up to the country inland.”[7] Procopius offers a detailed account of the terror of the plague and the death toll left in the wake, albeit sometimes the numbers seem inflated. “The plague lasted in Byzantium for four months and was at its peak for about three. At the beginning not many more people died than usual, then the disaster grew greater, and finally the number of dead reached five thousand a day, and then attained ten thousand and even more than this.”[8]


Most of the historians consider it to be a strain of the bubonic plague. Yersinia Pestis is the bacterium responsible for the bubonic plague. As for the transmission of the plague, the flea acted as a vector and arrived in ports on dogs, or more chiefly rats. Y. pestis spreads to humans by fleabites, and the deadliness of the plague is from its endotoxins, and the collection of fatty acids known as Lipid A. The transformation of a fleabite into bubonic plague is impossible without Lipid A.[9] The bacteria travels through the lymphatic system, which leads to the nodes in the throat, groin, and under the arms.[10] Most historians conclude that the plague was bubonic based on the descriptions of fever and buboes that develop around the infected nodes of the lymphatic system. These characteristics match up with Procopius’s account of the Justinian plague. “A bubonic swelling developed, not only where the part of the body under the stomach is also called the “bubon” but also within the armpit, and in some beside the ears and in places on the thighs.”[11]


The death rate of bubonic plague varies anywhere from forty to seventy percent of its cases. The reason offered for the fact that the plague only lasted for four months, is the rat and human populations died before perpetuating the disease.[12] The most important examination of the effects of the plague comes from a passage from Procopius in which he writes: “At that time it was not easy to see anyone in Byzantium out of doors; all those who were in health sat at home either tending to the sick or mourning the dead. If one did manage to see a man actually going out, he would be burying one of the dead. All work slackened; craftsmen abandoned all their crafts and every task which any man had inhand.”[13] This account is the immediate effect of the plague, in that daily life comes to a halt in the city and the work stoppage lasts for four months.


The account of Agathias, a lawyer born in Asia Minor sometime around 532, is useful in detailing the impact and providing corroborating testimony about the plague.[14] In stating the second wave of Justinian’s plague that began in 558, he writes: “During that year at the beginning of spring a second outbreak of plague swept the capital, destroying a vast number of people. From the fifteenth year of the reign of the Emperor Justinian when the plague first spread to our part of the world it had never really stopped, but had simply moved from one place to another, giving in this way something of a respite to those who had survived its ravages. It now returned to Constantinople almost as though it [had] been cheated on the first occasion into a needlessly hasty departure. People died in great numbers as though seized by a violent and sudden attack of apoplexy. Those who stood up to the disease longest barely lasted five days.”[15] He goes on to describe the people that were the most vulnerable to the disease, “People of all ages were struck down indiscriminately, but the heaviest toll was among the young and vigorous and especially among the men...”[16] The heavy loss of manpower is apparent based on the historical accounts of Procopius and Agathias. The ramifications of the shortage of manpower is clearly seen both militarily and economically.


The plague had a tremendous impact economically on the Byzantine Empire. For an empire that was still highly agrarian and depended heavily on taxation, one of the immediate effects from the plague was the loss of farmers. This affected the empire two fold, one would be a shortage of food and the second being loss of taxes from the former landholder. If the plague did have as big of an impact one would expect to see evidence of famines after the plague years, and that is exactly what happens. Famines occur in the empire in 542 and then again in the years of 545 and 546.[17] The diminished population also increased the financial hardships of an empire already paying heavily for the military campaigns, due to the loss of a larger taxpayer base.[18] One direct result was the tax of the deceased landholders fell to the responsibility of their neighbors as was the previous custom, and in 545 Justinian had to rule against this law to alleviate the financial burden. [19] In 544 there was another edict issued by Justinian in an attempt to curb inflation, and he froze both wages and prices at their pre plague levels.[20] These decrees indicate the volatile nature of the Byzantine economy.


Another factor that occurred at this time was a souring of relations between Persia and the Byzantine Empire, which resulted in several battles. Justinian was able to muster an army of thirty thousand men in 544, which seems to be the bulk of his remaining force to confront the Persians. A much smaller Persian force devastated the army.  Both sides continuously engaged in battles until a peace formed in 545, with Byzantium again agreeing to pay tribute to Persia. An interesting passage from Procopius’s account of the Persian battles occurs in 542. Belisarius, recalled from Italy, fought the Persians and succeeded in turning them back. Procopius writes that, “Belisarius secures the surrender of Sisauranon and sends Arethas across the Tigris on a raid.  In the meantime the army suffers from disease.”[21] The period for this passage is in the year 542 and could be an indication of the effects of the plague on the armies. Either way the battles between the Persians and the Byzantines were on a small scale.



The Byzantine empire under Justinian's reign, 527-565
Source: The Spiritual Pilgrim website

After the plague outbreak dissipated, Justinian turned his attention to the reconquest of the west. In 544 Belisarius received orders for Italy to deal with the impending siege of Rome at the hands of Totila. Totila recaptured most of Italy and besieged Rome in 546, while Belisarius had a small army of four thousand men comprised of mostly fresh recruits.[22] Rome fell, although Totila did not leave a garrison there, so Belisarius was able to reclaim it. Belisarius was incapable of defeating the Goths though so he pleaded with Justinian for more reinforcements, but unlike earlier they were not on the way. Constantinople recalled Belisarius in 549. Rome fell to Totila in the same year and it was not until 551 that Justinian finally sends Narse at the head of a thirty thousand man army to reclaim Italy.[23] By 552 Narse had conquered Ravenna and reclaimed Rome for the empire. Justinian had finally been able to field a suitably sized army of which he relied more heavily on barbarian mercenaries because of the plague. The army sent to Italy contained: “three thousand Herulian cavalry, two thousand Huns, four thousand Persian deserters, between ten and fifteen thousand imperial regulars largely from Thrace and Illyria, and nearly six thousand Lombard.” [24] It would have been impossible for the military to recover territory and win such decisive victories without the use of barbarians due to the loss of manpower from the plague.[25]



In addition to the campaign in Italy in 544, a revolt led by the Moors in Africa came to the attention of Justinian. Solomon was prefect of Africa and killed in a skirmish, forcing Justinian to send a new general to quell the rebellion. In 543 the plague arrived in Africa, and while the armies there eventually received reinforcements they never reached their previous strength.[26] By 546 the situation was dire, and Justinian dispatched John Troglita with a very small group of reinforcements to deal with the uprising.[27] By 548 the Byzantines had successfully defeated the Moors, but it was only due to the heavy influx of Berber mercenaries.[28]


The Byzantine campaign in Spain was on a small scale, but proved to be relatively successful. When the Visigoth Athangild led a rebellion to become king, he asked for assistance from Justinian. In 552 a small force of two thousand men arrived and was able to establish a foot hold on the Mediterranean coast. The combined force of the two armies was enough to establish Athangild as King, but removing the Byzantine Army proved to be an impossible task.[29] The foothold established in Spain represented the furthest extent of the reconquest undertaken by Justinian.


There is clear evidence of the impact the plague had on the military efforts of Justinian.  The death toll was too great even if it was not at the exaggerated levels reported by Procopius. How long it took to muster reinforcements was a good indicator of just how hard the empire was hit.  Italy reinforced at a quicker rate and orchestrated on a grander scale before the plague struck their campaign. The pre plague attack of Italy only took five years to end in a decisive manner, whereas the second campaign took eight years with a long gap that saw Belisarius desperate for reinforcements. Another example was the increased reliance on barbarian forces to supplement the Byzantine army. While there had always been the use of barbarian forces, the plague caused a steady increase in the numbers of barbarians.[30]


Agathias writes about the state of the army after the plague: “The Roman armies had not in fact remained at the desired level attained by the earlier Emperors but had dwindled to a fraction of what they had been and were no longer adequate to the requirements of a vast empire.  And whereas there should have been a total effective fighting force of six hundred and forty-five thousand men, the number had dropped during this period to barely one hundred and fifty thousand.”[31] This is not in reference to the direct effect of the plague, but is merely evidence of the fact the military reduced in size after the time of the plague.


The territorial empire created by Justinian barely outlasted him, and his dreams of reconquest were never fully realized. By 540 the Byzantine Empire had momentum, and was well on the way to retaking the former western Roman territories back. The Byzantines took Africa with little effort and brought Italy under control as well. Belisarius was granted reinforcements promptly when they were requested, not the case in the years after the plague struck. The plague had an immediate effect on both the economy and military capabilities of the Byzantine Empire. The two fold problems stemmed from one major factor, and that is the loss of manpower caused by the plague. Procopius demonstrates this both in his detailing of the rampant death toll and severe work shortage that resulted from Justinian’s plague. The famines and subsequent inflation that followed put the empire in trouble financially which also contributed to the shrinkage of the military force. While eventually the empire was able to recover from the plague and claim more land than before, the plague kept it from achieving greater glory.      



About the author

Joshua North is a senior at Armstrong State University, pursuing a major in history and minors in both Philosophy and Psychology.



Recommended citation

Joshua North, “The Death Toll of Justinian’s Plague and Its Effect on the Byzantine Empire,” Armstrong Undergraduate Journal of History 3, no. 1 (Jan. 2013).




[1]J.A.S. Evans, The Age of Justinian: The Circumstances of Imperial Power (New York: Routledge, 1996), 118.

[2]Dionysios Stathakopoulos, “Crime and Punishment: The Plague in the Byzantine Empire, 541–749” in Plague and the End of Antiquity: The Pandemic of 541750, ed. Lester K. Little (New York: Cambridge University Press, 2007), 99.

[3]Procopius, History of the Wars, Secret History, and Buildings, trans. and ed. Averil Cameron (New York: Washington Square Press, inc., 1967), 186.

[4]Procopius, 209.

[5]Ibid., 115.

[6]Ibid., 116.

[7]Ibid., 116. 

[8]Procopius, 119–120.

[9]William Rosen, Justinian’s Flea: The First Great Plague and the End of the Roman Empire (New York, Penguin Books, 2007), 208 and 209.

[10]Ibid., 209. 

[11]Procopius, 117. 

[12]Evans, 163, 210.

[13]Procopius, 121.

[14]Agathias, The Histories, trans. Joseph D. Frendo (New York: Walter de Gruyter & Co., 1975), IX.

[15]Ibid., 145. 

[16]Ibid., 145.

[17]Stathakopoulos, 116.

[18]Peter Sarris, Economy and Society in the Age of Justinian, (New York: Cambridge University Press, 2006), 218.

[19]Evans, 164.

[20]Rosen, 272.

[21]Procopius, 108. 

[22]Evans, 171.

[23]Ibid., 177.

[24]Rosen, 281.

[25]John L. Teall, “The Barbarians in Justinian’s Armies,” Speculum 40, no.2 (April 1965), 314.

[26]Ibid., 317.

[27]Ibid., 319. 

[28]Ibid., 317.

[29]Evans, 180.

[30]Teall, 319.

[31]Agathias, 148.

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