Siege of Thessalonica (676–678)

In the reign of Justinian I (r. 527–565), Slavic tribes (Sclaveni) had already appeared on the Danube frontier of the Byzantine Empire.[1] Over the next few decades, they raided into Thrace and Illyricum, while at times serving as mercenaries in the Byzantine army.[2][3] From the 560s, the Slav communities came under the control of the newly established Avar Khaganate. Raids became larger and resulted in permanent settlement, especially as the Avars were able to capture fortified cities, leading to loss of imperial control over the surrounding areas. While the Byzantines were preoccupied in the East against the Persians, the 580s saw ever deeper and more destructive raids in the Balkans, even into southern Greece. The same period saw the start of large-scale Slavic settlement in the Balkan hinterland.[4] After making peace with Persia, Emperor Maurice was able to launch a series of counterattacks that drove the Avars and their Slavic allies back, but the respite was short-lived: following the usurpation of Phocas in 602, and the start of another, and even more catastrophic, war with Persia, the Balkans were left nearly defenseless, and the Danube frontier collapsed once more, overrun by the Avars and Slavic tribes, who settled across the region.[5]

By the 610s, the city of Thessalonica was surrounded by large Slavic settlements, being reduced to itself within its wall, according to historian John Van Antwerp Fine, to "virtually a Roman island in a Slavic sea".[6] The first book of the Miracles of Saint Demetrius records the attempts by the Slavs to capture the city in that time, first an unsuccessful attack by the Slavic leader Chatzon in c. 615, followed by an unsuccessful siege by the Avars and Slavs in 617.[7] By the middle of the 7th century, more cohesive Slavic coalitions (Sclaviniae) had been established in the former Roman Balkans. The only imperial reaction came in 658, when Emperor Constans II campaigned in Thrace, brought many Sclaviniae under imperial control, and relocated many Slavs to Asia Minor.[8]

7th-century mosaic from the Cathedral of St. Demetrius in Thessalonica, depicting the saint with the city's archbishop (left) and the eparch (right)

The second book of the Miracles of Saint Demetrius names Perboundos, the "king of the Rhynchinoi",[lower-alpha 1] as a powerful ruler, who was sufficiently assimilated to be able to speak Greek, had relations with Thessalonica to the point of maintaining a residence there, and even dressed in the Byzantine style.[9][10] According to the Miracles, the peace existing between the Slavs and the Byzantines ended when the—unnamed—Byzantine eparch of Thessalonica was informed that Perboundos planned to move against the city. The eparch reported this to the Byzantine emperor, who ordered his arrest. After informing the city elders, the eparch had Perboundos arrested during his stay in the city, put in irons and sent to the Byzantine capital, Constantinople.[11][12][13]

The Rhynchinoi, along with a Slavic tribe living in the neighbouring Strymon valley, the Strymonitai, were greatly upset by Perboundos' arrest. At their request, a joint delegation including Thessalonian envoys went to Constantinople to intercede on his behalf—a unique event, according to Byzantinist Paul Lemerle, that illustrates the surprisingly close and amicable relationship between the Byzantine city and its "barbarian" neighbours. The phrasing of the Miracles makes clear that Perboundos was guilty of some transgression, since the embassy was sent to request clemency but not exoneration. The emperor, who was in the midst of extensive preparations for a war with the Arabs, promised to set Perboundos free once the war was over. The envoys were apparently satisfied with this, and returned home; the agitation among the Slavs subsided for the moment.[14][15] Subsequent events proved the eparch's suspicions well-founded. Perboundos managed to escape with the aid of an imperial translator charged with affairs concerning the Slavic tribes. A large-scale manhunt was launched against Perboundos, and fears of an imminent Slavic move on Thessalonica led the emperor to send a swift dromon to warn the city and instruct its leaders to take precautions and stockpile food in case of a siege. After forty days Perboundos was found hiding on the translator's estate near Bizye. The translator was executed, but Perboundos was returned to confinement in Constantinople, as before. After another failed attempt to escape, he publicly proclaimed his intention of raising all the Slavic tribes in revolt and seizing Thessalonica. Following his confession, he was executed.[11][16][17]

On receiving news of Perboundos' execution, the Rhynchinoi rose in revolt,[18] soon joined by the Strymonitai and another neighbouring tribe, the Sagoudatai.[lower-alpha 2] Many other Slavic tribes, however, did not join the revolt, and some, like the Belegezitai, proved willing to assist the Roman side.[19]

Arrival of the Byzantine squadron and the great Slavic assault

The Byzantine city wall of Thessalonica

Some relief was provided by the arrival of a squadron of ten armed transports, all that the emperor could spare, as he was engaged "in the other war" with the Arabs. However, according to the author of the Miracles, the sailors took advantage of the Thessalonians, and sold them the grain they had brought at highly inflated prices, while the authorities used them as manpower to seek out any hidden caches of grain in the city. The new arrivals were not sufficient to prevent the Slavs from operating freely in the city's environs; anyone who ventured outside the city walls, by land or sea, seeking food was in danger of attack.[27] As a result, an assembly of the citizens and the local council decided to send the ten vessels, along with whatever watercraft could be found in the city, manned by the most vigorous citizens, to obtain food from the Belegezitai, who were living at the shores of the Pagasetic Gulf in Thessaly.[28]

Their absence was noted and the Slavs decided to exploit the absence of so many defenders to assault the city. They asked the assistance of the Drougoubitai, a large tribe, or confederation of tribes, living northwest of Thessalonica, who possessed the knowledge of making siege engines. The extent of the participation of the Drougoubitai in the siege is unclear; according to Lemerle, they likely provided only the engines and perhaps their crews. Thus reinforced, the Slavs launched their decisive attack on 25 July "of the fifth indiction" (677).[29][30]

According to the account of the Miracles, the first miraculous intervention of Saint Demetrius caused the Strymonitai to halt and turn back once they were three miles from the city walls; the reasons for this defection are unknown, but it effectively left only the Rhynchinoi and the Sagoudatai to carry the brunt of the fighting.[31] Due to the hagiographic nature of the Miracles, and the use of common literary topoi, gleaning details about the fighting from the account is difficult; certainly the siege engines provided by the Drougoubitai are not mentioned as playing any particular role in the events. Over three days, from 25 until 27 July, the Slavs launched attacks on the city walls but were repelled by the defenders, with the aid, according to the Miracles, of Saint Demetrius himself, who intervened numerous times to repel the assaults. Most notably he is recorded as appearing in person, on foot and bearing a cudgel, to repel an attack by the Drougoubitai against a postern at a place called Arktos—an event which some modern commentators have interpreted as indicating that the Slavs penetrated into the city. On the evening of the 27th, the Slavs abandoned the assault and withdrew, taking their fallen with them, but abandoning the siege engines, which were taken by the Thessalonians into the city.[20][32] A few days later, the expedition sent to Thessaly returned, laden with wheat and dried vegetables.[33]

Emperor Constantine IV and his retinue, mosaic in the basilica of Sant'Apollinare in Classe, Ravenna

The Miracles mention no specific date other than the "fifth indiction", leading to speculation by modern scholars as to the timing of these events. Some scholars followed the proposal of the nineteenth-century Austrian historian T. L. Tafel, who placed the events in 634, but the then reigning emperor, Heraclius (r. 610–641) was not in Constantinople, nor had the conflict with the Arabs begun.[39] Hélène Antoniades-Bibicou and Halina Evert-Kappesova suggested a different reconstruction, with the arrest of Perboundos occurring in 644, followed by the two-year siege of Thessalonica, with the great Slavic assault on the "fifth indiction" in 647, followed by an imperial campaign against the Strymonitai in 648/649.[40] Charles Diehl and others identified the latter with Constans II's campaign in 657–658;[41] Henri Grégoire suggested 692 as the date of the general assault, but the Byzantines and Arabs were at peace in the years prior to then.[42] Another theory, supported by Francis Dvornik and Konstantin Jireček among others, identified the campaign at the end of the siege with the expedition launched by Justinian II (r. 685–695, 705–711) in 687/688, when the emperor led in person a campaign through Thrace and Macedonia up to Thessalonica, thus restoring the overland connection between the latter and Constantinople. This would place the siege in the years 685–687, but once again, these years were a period of peace with the Arabs.[43][44]

The chronology accepted today by most scholars[45] is that established by Paul Lemerle in his critical edition of the Miracles, which relies on a number of factors: the great time elapsed since the previous Slavic sieges, as inferred from the narrative, points to an exclusion of earlier dates; the emperor reigning during the siege was the same as that reigning when the account was compiled, which excludes Justinian II, since his arrival in person in Thessalonica would have been mentioned by the author; and the emperor's preoccupation with a conflict with the Arabs, which removes 662, when the Arabs were in peace with Byzantium due to the First Fitna. This leaves 676/677, when the Byzantines under Constantine IV (r. 668–685) were confronted with the huge attack launched by the Umayyad Caliphate in 671/672, that culminated in the Siege of Constantinople in 674–678, as the only "fifth indiction" that matches all the facts described in the source.[46] The reconstructed chronology that Lemerle suggested places the arrest and execution of Perboundos sometime in early 676, with the Slavic alliance starting the siege in summer 676 and culminating in the great assault against Thessalonica in July 677. The imperial expedition against the Strymonitai, and the lifting of the siege, took place in summer 678, following the destruction of the Arab fleet and the end of the Arab threat to Constantinople.[47][48] The Greek scholar Andreas Stratos proposes an even longer time-frame, with the Perboundos affair taking place sometime in 672–674, his execution taking place in 674/675, just as the Arab siege began in earnest, followed by the start of the Slavic attacks on Thessalonica in 675. In the rest, he too follows Lemerle's chronology.[48]

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