He panicked and backed the loser. The great battle ended with Pompey losing the civil war, and his head, and Caesar triumphant - and still Cicero's political radar continued to malfunction. Fortunately, Caesar pardoned him, but no sooner had he snuggled up to the great dictator than the Ides of March left Cicero unprotected again.
Along the way, he had displayed a tremendous lack of political wit by making an enemy of Mark Antony, who now became convinced that Cicero had been on the side of Caesar's backstabbers.
At this crucial juncture, Cicero took the rash step in a series of speeches of denouncing Antony, who was guilty of "incredible folly … profligacy and debauchery", a man "devoid of humanity and ignorant of the common usages of life".