The remaining days of Februarius brought despair for Pompey's supporters, joy for Caesar's.
Flush with an unbroken chain of victories, Caesar continued his southward advance and surrounded Corfinium. Domitius Ahenobarbus, trapped in the city, sent desperate messages to Pompey begging for reinforcements. Pompey curtly replied that he had no intention of relieving Corfinium because Domitius had no business making a stand there in the first place.
Domitius concealed the contents of the letter from his officers and claimed that Pompey was on his way, but his agitated demeanor fooled no one. Behind his back, his officers decided to hand the city over to Caesar without a fight.
Domitius's longstanding grudge against Caesar was personal. Domitius's grandfather and father had begun the settlement of southern Gaul, conquering the Allobroges and the Arverni, building roads, establishing Roman colonies on the coast, and along the way amassing an enormous family fortune. The family had come to think of the region as their personal domain, to which Domitius should be heir. Caesar they considered an upstart who had built on their achievements to launch his own conquests. When Domitius made his first bid to acquire governorship of southern Gaul, six years ago, Caesar successfully thwarted him and held on to command of the region. Now Caesar's tenure had at last expired. Legally he was obliged to relinquish Gaul and let Domitius succeed him. Caesar's answer had been to cross the Rubicon with his army. Domitius had good reason to hate him, and better reason to fear him.
Finding himself betrayed and despairing of an ignoble death at the hands of Caesar or, even more ignobly, at the hands of his own rebellious men, Domitius asked his physician to give him poison. No sooner had Domitius swallowed the dose than word arrived that Caesar was treating all captives, even his bitterest enemies, with mercy and respect. Domitius wailed and tore his hair and cursed himself for acting too soon- until the physician, who knew his master better than his master knew himself, revealed that the dose was not poison, but a harmless narcotic. Domitius surrendered to Caesar and was allowed to keep his head.
In Rome, copies of Caesar's public pronouncement on entering Corfinium were posted in the Forum by his supporters:
I did not leave my province with intent to harm anybody. I merely want to protect myself against the slanders of my enemies, to restore to their rightful positions the tribunes of the people, who have been expelled because of their involvement in my cause, and to reclaim for myself and for the Roman people independence from the domination of a small clique.
Fence-sitters among the rich and powerful were heartened by the news of Caesar's clemency. Some who had fled now began to return to the city.
His army swelled by the troops of Domitius Ahenobarbus and by fresh reinforcements from Gaul, Caesar continued his southward advance. Pompey fell back and ordered all loyalist troops to rendezvous at Brundisium, in the heel of Italy.