In 49 BC, the last Republican civil war was initiated after Julius Caesar defied senatorial orders to disband his army following the conclusion of hostilities in Gaul. He crossed over the Rubicon river with the 13th Legion, a clear violation of Roman Law, and marched to Rome. The Optimates fled to Greece under the command of Pompey since they were incapable of defending the city of Rome itself against Caesar. Led by Caesar, the Populares followed, but were greatly outnumbered and defeated in the Battle of Dyrrhachium. Still outnumbered, Caesar recovered and went on to decisively defeat the Optimates under Pompey at Pharsalus. Pompey then fled to Egypt, where to Caesar's consternation, Pompey was assassinated. The remaining Optimates, not ready to give up fighting, clustered in the African