During the civil war he fought on the side of Otho against Vitellius, and obtained a considerable success against Aulus Caecina Alienus (one of the Vitellian generals) near Cremona, but did not follow it up. When Caecina had been joined by Fabius Valens, Paulinus advised his colleagues not to risk a decisive battle, but his advice was disregarded, and Otho (q.v.) was utterly defeated at Bedriacum.
The fleet was at once despatched to secure Liguria, and on the 14th of March Otho, undismayed by omens and prodigies, started northwards at the head of his troops in the hopes of preventing the entry of the Vitellian troops into Italy.
The Vitellian commanders now resolved to bring on a decisive battle, and their designs were assisted by the divided and irresolute counsels which prevailed in Otho's camp. The more experienced officers urged the importance of avoiding a battle, until at least the legions from Dalmatia had arrived.
At a short distance from that city they unexpectedly encountered the Vitellian troops.