Treaty of Devol

The Treaty of Deabolis (Greek: συνθήκη της Δεαβόλεως) was an agreement made in 1108 between Bohemond I of Antioch and Byzantine Emperor Alexios I Komnenos, in the wake of the First Crusade. It is named after the Byzantine fortress of Deabolis (modern Devol, Albania). Although the treaty was not immediately enforced, it was intended to make the Principality of Antioch a vassal state of the Byzantine Empire.

At the beginning of the First Crusade, crusader armies assembled at Constantinople and promised to return any land they might conquer to the Byzantine Empire. However, Bohemond, the son of Alexios' former enemy Robert Guiscard, claimed Antioch for himself. Alexios did not recognize the legitimacy of the principality, and Bohemond went to Europe looking for reinforcements. He initiated open warfare against Alexios, laying siege to Dyrrhachium, but was soon forced to surrender and negotiate with Alexios at the imperial camp at Deabolis, where the Treaty was signed.

Under the terms of the Treaty, Bohemond agreed to become a vassal of the emperor and to defend the Empire whenever needed. He also accepted the appointment of a Greek patriarch. In return, he was given the titles of sebastos (noble) and doux (duke) of Antioch, and he was guaranteed the right to bequeath the County of Edessa to his heirs. After this treaty was signed, Bohemond retreated to Apulia and died there. His nephew, Tancred, who was his regent in Antioch, refused to accept the terms of the treaty. Antioch came temporarily under Byzantine sway in 1137, but it was not until 1158 that it truly became a Byzantine vassal.

The Treaty of Deabolis is viewed as a typical example of the Byzantine tendency to settle disputes through diplomacy rather than warfare, and was both a result of and a cause for the distrust between the Byzantines and their Western European neighbors.

In 1097, the crusader armies assembled at Constantinople having traveled in groups eastward through Europe. The Byzantine Emperor Alexios I Komnenos, who had requested only some western knights to serve as mercenaries to help fight the Seljuk Turks, blockaded these armies in the city and would not permit them to leave, until their leaders swore oaths promising to restore any land formerly belonging to the empire they might conquer on the way to Jerusalem. The crusaders eventually swore these oaths, individually rather than as a group. In return, Alexios gave them guides and a military escort. The crusaders were however exasperated by Byzantine tactics, such as negotiating the surrender of Nicaea from the Seljuks while it was still under siege by the crusaders, who hoped to plunder it to help finance their journey. The crusaders, feeling betrayed by Alexios, who was able to recover a number of important cities and islands, and in fact much of western Asia Minor, continued on their way without Byzantine aid. In 1098, when Antioch had been captured after a long siege and the crusaders were in turn themselves besieged in the city, Alexios marched out to meet them, but hearing from Stephen of Blois that the situation was hopeless, he returned to Constantinople. The crusaders, who had unexpectedly withstood the siege, believed Alexios had abandoned them and considered the Byzantines completely untrustworthy. Therefore, they regarded their oaths to have been invalidated.

By 1100, there were several crusader states, including the Principality of Antioch, founded by Bohemond I in 1098. It was argued that Antioch should be returned to the Byzantines, despite Alexios's supposed betrayals, but Bohemond claimed it for himself. Alexios, of course, disagreed; Antioch had an important port, was a trade hub with Asia and a stronghold of the Eastern Orthodox Church, and was the host of the important Eastern Orthodox patriarch of Antioch. It had only been captured from the empire a few decades ago, unlike Jerusalem, which was much farther away and had not been in Byzantine hands for centuries. Alexios therefore did not recognize the legitimacy of the Principality, believing it should be returned to the Empire according to the oaths Bohemond had sworn in 1097. He therefore set about trying to evict Bohemond from Antioch.

Bohemond then provoked more enmity from both Alexios and the Eastern Orthodox Church in 1100, when he appointed Bernard of Valence the Latin patriarch, and at the same time expelled the Greek patriarch, John the Oxite, who fled to Constantinople. Soon thereafter, Bohemond was captured by the Danishmends of Syria and was imprisoned for three years, during which the Antiochenes chose his nephew Tancred as regent. After Bohemond was released, he was defeated by the Seljuks at the Battle of Harran in 1104; this defeat led to renewed pressure on Antioch from both the Seljuks and the Byzantines. Bohemond left Tancred in control of Antioch and returned to the West, touring Italy and France for reinforcements. He won the backing of Pope Paschal II and the support of the French King Philip I, whose daughter he married. It is unclear whether his expedition had qualified as a crusade.

Bohemond's Norman relatives in Sicily had been in conflict with the Byzantine Empire for over 30 years; his father Robert Guiscard was one of the Empire's most formidable enemies. While Bohemond was away, Alexios sent an army to reoccupy Antioch and the cities of Cilicia. In 1107, having organized a new army for his planned crusade against the Muslims in Syria, Bohemond instead initiated open warfare against Alexios, crossing the Adriatic to lay siege to Dyrrhachium, the westernmost city of the Empire. However, much like his father, Bohemond was unable to make any significant advances into the Empire's interior; Alexios avoided a pitched battle and Bohemond's siege failed, partly due to a plague among his army. Bohemond soon found himself in an impossible position, isolated in front of Dyrrhachium: his escape by sea was cut off by the Venetians, and Paschal II withdrew his support.