The Roman republic, still in the midst of the political, social, and economic revolution whose first phase was the awful civil wars of Marius and Sulla, had long been at the mercy of Pompey the opportunist, Crassus the plutocrat, and Julius Caesar—­the first Triumvirate.  Crassus had always leaned towards Caesar and the entente between Caesar and Pompey had been strengthened by the marriage of the latter with Caesar’s daughter Julia, who was to die in the midst of the crisis 54 B.C.  In 58 B.C., the year following this marriage, Caesar went to take up his great command in the Gauls, but Pompey remained in Rome, where every day his influence and popularity were failing while the astonishing successes of Caesar made him the idol of the populace.  In 55 B.C.  Pompey was consul for the second time with Crassus.  He received as his provinces the two Spains, but he governed them by his legates and remained in the neighbourhood of the City.  Crassus received the province of Syria, and the appalling disasters of the Parthian war, in which he most miserably lost life and honour, seemed to give Pompey the opportunity for which he had long been waiting.  He encouraged the growing civil discord which was tearing the state in pieces, and with such success that the senate was compelled to call for his assistance.  In 52 B.C. he became sole consul, restored order, and placed himself at the head of the aristocratic party which he had deserted to become the great popular hero when he was consul with Crassus in 70 B.C.

Now Caesar had long watched the astonishing actions of Pompey, and had no intention of leaving the fate of the republic to him and the aristocracy.  He does not seem to have wished to break altogether with Pompey, but only to hold him in check.  At his meeting with Pompey at Luca (Lucca) in 56 B.C. he had been promised the consulship for 48 B.C. when his governorship came to an end, and he now determined to insure the fulfilment of this promise which would place him upon a legal equality with his rival.  For the rest he knew that he was as superior to Pompey as a statesman as he was as a soldier, and he did not apparently anticipate any difficulty in out-manoeuvring him in the senate and in the forum.  Caesar, then, claimed no more than an equality with Pompey and the fulfilment of his promise; but these he determined to have.  All through the winter of 52-51 B.C. he was arming.  Well served by his friends, among whom were Mark Antony and Curio the tribunes, in 50 B.C., “having gone the circuit for the administration of justice,” as Suetonius tells us, “he made a halt at Ravenna resolved to have recourse to arms if the senate should proceed to extremity against the tribunes of the people, who had espoused his cause.”  But first he determined for many reasons to send ambassadors to Rome, to request the fulfilment of the promise made to him at Luca.  Pompey, who was not yet at open enmity with him, determined, although he had made the promise, neither to aid him by his influence nor openly to oppose him on this occasion.  But the consuls Lentulus and Marcellus, who had always been his enemies, resolved to use all means in their power to prevent him gaining his object.