He held the title of sparapet (commander-in-chief), which was the hereditary right of the Mamikonian family.
Manuel and his brother Koms (or Kon) were taken captive by the Sasanians and sent to fight against the Kushans.
Manuel then crowned as co-rulers the two young sons of the former king Pap of Armenia, Arshak and Vagharshak.
Armies under generals such as Varaz were sent to invade Armenia but were defeated by Manuel.
The modern Armenian historian Hakob Manandian, on the other hand, believes that Manuel accepted Sasanian suzerainty over Armenia.