Meanwhile, the strength of Arab assaults continued to increase. Theodore eventually concluded a truce with then governor of Syria, Muawiyah I in 651, and Arabs concentrated their efforts against the remaining pockets of resistance in the Sassanid Empire. Finally, by 652 Rshtuni, despairing of further resistance, accepted Muawiyah's suzerainty and was appointed ruler of Armenia. Rshtuni was able to negotiate a treaty that left Armenia with a relatively high level of autonomy. In response, Constans personally marshaled his forces and led them to Armenia despite a growing plot against him in Constantinople, ironically by the Armenian commander of the Army of Thrace. Constans secured Armenia and deposed Theodoros, who took refuge on the island of Akhtamar. A Byzantine commander named Maurianus was given the task to defend the Armenian frontier. In 654 Maurianus was driven out of Armenia into the Caucasus and Theodoros was restored. Deciding that Theodoros was untrustworthy, the Arabs sent him to Damascus, where he died in captivity the following year. He was replaced as prince by his son-in-law, Hamazasp Mamikonian. His body was brought to his home district of Rshtunik, where he was buried in the tomb of his forefathers.