Theodosius III

After the Umayyad Caliphate was repelled in the first Arab siege of Constantinople (674–678), the Arabs and Byzantines experienced a period of peace,[1] with hostilities again engaged by Byzantine Emperor Justinian II (r. 685–695, 705–711), resulting in a string of Arab victories, and the loss of control over the Armenia and the Caucasian principalities for the Byzantines, as well as a gradual encroachment upon Byzantine borderlands. Yearly, generals from the Caliphate would launch raids into Byzantine territory, seizing fortresses and towns.[2][3][4] After 712, the defensives of the Byzantine Empire began to weaken, Arab raids began to penetrate deeper into Byzantine Asia Minor, and Byzantine response to these raids became more scarce.[5][6] The success of these raids emboldened the Arabs, who had begun to prepare for a second assault as early as the reign of Caliph al-Walid I (r. 705–715); following his death, his successor, Sulayman (r. 715–717) continued planning the campaign,[7][8][9][10][11] Sulayman began assembling his forces in the plain of Dabiq, north of Aleppo, entrusting the command of these forces to his brother Maslama ibn Abd al-Malik.[12]

Simultaneous to the threat of the Arabs, the Slavs and Bulgarians were a growing threat to the northern frontier of the Byzantine Empire, threatening Byzantine control in the Balkans and Greece.[13] During the rule of Byzantine Emperor Philippikos Bardanes (r. 711–713), in 712, the Bulgarians under Khan Tervel advanced as far as the walls of Constantinople itself, plundering the surrounding country, including the villas and estates near the capital, where the Byzantine elites often summered.[14]

Sulayman's preparations, including his construction of a war fleet, were quickly noticed by the Byzantine Empire. Emperor Anastasios II (r. 713–715) began making preparations to defend against this new onslaught, including sending the patrician and urban prefect, Daniel of Sinope to spy on the Arabs, under the pretense of a diplomatic embassy, as well as shoring up the defences of Constantinople,[15][16][17] and strengthening the Byzantine Navy. Theophanes states (A.M. 6206) that in early 715 Anastasius had commanded the elements of the navy to gather at Rhodes to then advance to Phoenix–usually identified with modern Finike in Lycia, it may also be modern Fenaket across Rhodes,[18] or perhaps Phoenicia (modern Lebanon), famed for its cedar forests.[5][19][20][11][21] It was there that the Opsikians mutinied against their commander, John the Deacon, killing him before sailing for Adramyttium, and there declared Theodosius, a tax collector, as Emperor Theodosius III.[5][19][20][11] Following this, according to Theophanes (A.M. 6207):[22]

When the malefactors arrived at Adramyttium, being leaderless they found there a local man named Theodosius, a receiver of public revenues, non-political and a private citizen. They urged him to become Emperor. He, however, fled to the hills and hid. But they found him and forced him to accept acclamation as Emperor.[22]

He was therefore acclaimed, allegedly unwillingly, as Emperor Theodosius III by the troops at Adramyttium in c. May 715.[23][22] Anastasios led his armies into Bithynia in the Opsician Theme to crush the rebellion, however, rather than remaining to fight Anastasios, Theodosius instead led his fleet to Chrysopolis, across the Bosporus from Constantinople. From Chrysopolis, he launched a six-month-long siege against Constantinople, before supporters within the city managed to open the gates for him, allowing him to seize the city in November 715.[23][24][25][26] Anastasios remained at Nicaea for several months, before finally agreeing to abdicate and retire to a monastery.[23][24][25][26]

One of Theodosius' first acts as emperor was to reinstate the image of the Sixth Ecumenical Synod, which Emperor Philippicus Bardanes had removed, earning himself the epithet of "orthodox" in the Liber Pontificalis for this action.[23][lower-alpha 1] The accession of Theodosius, which Byzantine sources convey as being both unwilling and incapable, viewed as a puppet emperor of the Opsicians, was not recognized as legitimate by many other themes, especially the Anatolics and the Armeniacs under their respective strategoi (generals) Leo the Isaurian and Artabasdos.[27][28] Leo proclaimed himself Byzantine emperor in the summer of 716,[28][29][30] and sought the support of the Arabs, who viewed the Byzantine disunity as advantageous, and thought the confusion and weakening of the Byzantine Empire would make it easier to take Constantinople.[31][32] Theodosius negotiated a treaty with the Bulgarian Khan Tervel, likely in order to secure their support against an imminent Arab attack against the Byzantine Empire. The treaty fixed the border between the Byzantine Empire and the Bulgarian Empire at Thrace, ceding the Zagoria region to the Bulgarians, as well as stipulating tribute payment to the Bulgarians, the return of fugitives, and some trade agreements.[23]

Leo began to march his troops to Constantinople soon after declaring himself emperor, first capturing Nicomedia, where he found and captured, among other officials, Theodosius's son, and then marched to Chrysopolis. After his son was captured, Theodosius, taking the advice of Patriarch Germanus and the Byzantine Senate, negotiated with Leo in spring 717, agreeing to abdicate and recognize Leo as emperor.[23][28][33][34][35] Leo entered Constantinople and definitively seized power on 25 March 717, allowing Theodosius and his son to retire to a monastery as monks.[28][33][34][35]

The Chronicle of Joshua the Stylite gives a different narrative, stating that:[36]

When the Emperor (Theodosius Constantine) saw a host was marching against him and that his military commander, Leo by name, had negotiated with them, his heart quaked and his hands shook. He resigned the empire, put down the crown and shaved his head. For there is a custom among Roman emperors, if one of them resigns the empire, he shaves his head and stays in his house, having from that time on no entourage. This one acted likewise. Even when Leo, the military commander, sent him a message, saying: "Strengthen yourself and fear not!" he was not persuaded and firmly resigned the empire.

After his retirement to a monastery, Theodosius became bishop of Ephesus.[23] He died at some point after he abdicated, and either he or his son are buried in the Church of St. Philip in Ephesus.[23]

Graham Sumner, the Byzantine historian, suggests that Theodosius might be the same person as Theodosius, the son of Emperor Tiberius III (r. 692–705). He was bishop of Ephesus by c.729, who held this position until his death, sometime after 24 July 754, and was a leading figure of the iconoclastic Council of Hieria in 754.[37] Byzantine historians Cyril Mango and Roger Scott do not view this theory as likely, as it would mean that Theodosius had to have lived for thirty more years after his abdication.[23]