Abgar II (ruled 68–53 BC) was a Syriac prince of Edessa in Osroene (today part of eastern Turkey). In 64 BC He sided with the Romans helping Pompey's legateLucius Afranius when the latter occupied northern Mesopotamia, but it is alleged that he helped to betray Marcus Crassus by leading him out onto an open plain, resulting in 53 BC in the Battle of Carrhae, which destroyed an entire Roman army. What is certain is that he gained no benefits from the battle, since shortly after he was deposed by Orodes II in a move to strengthen Parthian control over the region.
References
Han J. Drijvers & John F. Healey; The Old Syriac Inscriptions of Edessa and Osrhoene (1999)