Tilbeşar (Arabic Tall Bāshir, Turbessel (Frankish)) is a city in south-eastern Turkey.
It was a part of the Byzantine Empire, but came under control of local Armenian lords in the late 11th century. As a part of the County of Edessa it was one of the main strongholds of the Frankish counts. After the fall of Edessa to Zengi it was eventually sold to the Emperor Manuel I Comnenus in 1150 and fell to the Muslims within the year. The Byzantine Empire is the term conventionally used to describe the Roman Empire during the Middle Ages, centered at its capital in Constantinople. ... The County of Edessa was one of the Crusader states in the 12th century, based around a city with an ancient history and an early tradition of Christianity (see Edessa). ... Imad ad-Din Zengi (also Zangi or Zengui) (1087-1146) was the son of Aq Sunqur al-Hajib, governor of Aleppo under Malik Shah I. He became atabeg of Mosul in 1127, and of Aleppo in 1128, uniting the two cities under his personal rule, and was the founder of... Fresco of Manuel I Manuel I Comnenus Megas (November 28, 1118? - September 24, 1180) was Byzantine Emperor from 1143 to 1180. ...
He was joined by Joscelin of Courtenay[?], who became lord of the fortress of Turbessel on the Euphrates, an important outpost against the Seljuk Turks.
Joscelin continued to rule in his lands west of the Euphrates, centered around Turbessel, until 1149, when he was captured in battle by Zengi's son Nur ad-Din, and soon died.
His wife sold what was left of the County to the Byzantine Emperor Manuel I Comnenus, and its remaining strong points were captured by Nur ad-Din and the Sultan of Rum within the next year.