Encouraged by Cicero , the Senate denounced Antony . In January 43 they granted Octavian imperium ( commanding power ) , and sent him to relieve the siege . Encouraged by Cicero , the Senate denounced Antony and in January 43 they granted Octavian imperium ( commanding power ) , which made his command of troops legal and sent him to relieve the siege , along with Aulus Hirtius and Gaius Vibius Pansa Caetronianus , the consuls for 43 BC .