Tiberius II Constantine was Eastern Roman emperor from 578 to 582. Tiberius rose to power in 574 when Justin II, during an abatement in a period of severe mental illness, proclaimed him caesar and adopted him as his own son. In 578, the dying Justin II gave him the title of augustus, thus making Tiberius co-emperor alongside him. Tiberius became sole ruler less than two weeks later, assuming the regnal name of Constantine under which he reigned until his death. Tiberius' reign was marked by warfare with the Persians, as well as Avar incursions into the empire.