When Emperor Anastasius died in 518, Justin was proclaimed the new emperor, with significant help from Justinian. During Justin's reign (518–527), Justinian was the emperor's close confidant. Justinian showed a lot of ambition, and it has been thought that he was functioning as virtual regent long before Justin made him associate emperor on 1 April 527, although there is no conclusive evidence of this. As Justin became senile near the end of his reign, Justinian became the "de facto" ruler. Following the general Vitalian's assassination presumed to be orchestrated by Justinian or Justin, Justinian was appointed consul in 521 and later commander of the army of the east. Upon Justin's death on 1 August 527, Justinian became the sole sovereign.