Amidst the instability of the Year of the Four Emperors, Antonius Primus, a general who had loyally served Vespasian, took a decisive step in the political landscape of Rome when he entered the city proclaiming Vespasian as the rightful emperor. Following the chaotic aftermath of Nero's downfall, Rome was ripe with competing claims for the imperial throne, leading to a tumultuous power struggle among claimants. On this significant day, Primus entered the capital with both military force and popular support, emphasizing Vespasian’s military accomplishments and his lineage as pivotal to restoring order in the empire.

Antonius Primus was initially one of the generals who supported Vespasian's rise amid the civil unrest. As Vespasian stood in Judea, quelling a revolt, Primus saw an opportunity to strengthen their claim. His entry into Rome served not only as a military maneuver but also as a political statement, showcasing the necessity for unity under a strong leader. The populace, weary of the violence and instability from the civil wars, largely supported Primus's declaration, favoring Vespasian's promise of stability over continued conflict.

The atmosphere in Rome was electrified, with soldiers and citizens rallying behind Primus and his cause. The presentation of Vespasian as the key to ending the civil conflicts resonated deeply among the factions vying for power. As his arrival marked a significant political shift, it also played a crucial role in Vespasian eventually being recognized as Emperor, establishing the Flavian dynasty. This moment would not only define the future of the Roman leadership but also solidify Vespasian's rule and bring about essential reforms during a time fraught with chaos.