For centuries, Rome and Parthia had dominated the Middle East and antagonized each other. During that period, several invasions of Parthian territory were led by Roman leaders, most notably the failed campaign of Crassus and the conquest of Mesopotamia by Trajan. In the early 210s, a civil war broke out in the Parthian Empire, where Artabanus IV rose up against his brother Vologases VI. Artabanus quickly established control of most of the western territories, bringing him into contact with the Roman Empire. At this point, the Roman emperor Caracalla, who considered himself a second Alexander, decided to take advantage from the Parthian conflict. He proposed an alliance to Artabanus, and even asked to marry his daughter. When the alliance was agreed upon, Caracalla with his army entered Mesopotamia unopposed, ostensibly to meet his ally and future father-in-law. But when he came upon Artabanus and his court, Caracalla treacherously attacked and slew many of them. Artabanus escaped, but the Romans were free to plunder the lands east of the Tigris before returning to Edessa for the winter.