After Caesar had, at the conference of Luca in April 698, agreed to considerable concessions as regarded Pompeius, and the regents had thus placed themselves substantially on a level, their relation was not without the outward conditions of durability, so far as a division of the monarchical power - in itself indivisible - could be lasting at all. It was a different question whether the regents, at least for the present, were determined to keep together and mutually to acknowledge without reserve their title to rank as equals. That this was the case with Caesar, in so far as he had acquired the interval necessary for the conquest of Gaul at the price of equalization with Pompeius, has been already set forth.

But Pompeius was hardly ever, even provisionally, in earnest with the collegiate scheme. His was one of those petty and mean natures, towards which it is dangerous to practise magnanimity; to his paltry spirit it appeared certainly a dictate of prudence to supplant at the first opportunity his reluctantly acknowledged rival, and his mean soul thirsted after a possibility of retaliating on Caesar for the humiliation which he had suffered through Caesar's indulgence. But while it is probable that Pompeius in accordance with his dull and sluggish nature never properly consented to let Caesar hold a position of equality by his side, yet the design of breaking up the alliance doubtless came only by degrees to be distinctly entertained by him. At any rate the public, which usually saw better through the views and intentions of Pompeius than he did himself, could not be mistaken in thinking that at least with the death of the beautiful Julia - who died in the bloom of womanhood in the autumn of 700 and was soon followed by her only child to the tomb - the personal relation between her father and her husband was broken up. Caesar attempted to re-establish the ties of affinity which fate had severed; he asked for himself the hand of the only daughter of Pompeius, and offered Octavia, his sister's grand-daughter, who was now his nearest relative, in marriage to his fellow-regent; but Pompeius left his daughter to her existing husband Faustus Sulla the son of the regent, and he himself married the daughter of Quintus Metellus Scipio. The personal breach had unmistakeably begun, and it was Pompeius who drew back his hand. It was expected that a political breach would at once follow; but in this people were mistaken; in public affairs a collegiate understanding continued for a time to subsist. The reason was, that Caesar did not wish publicly to dissolve the relation before the subjugation of Gaul was accomplished, and Pompeius did not wish to dissolve it before the governing authorities and Italy should be wholly reduced under his power by his investiture with the dictatorship.

It is singular, but yet readily admits of explanation, that the regents under these circumstances supported each other; Pompeius after the disaster of Aduatuca in the winter of 700 handed over one of his Italian legions that were dismissed on furlough by way of loan to Caesar; on the other hand Caesar granted his consent and his moral support to Pompeius in the repressive measures which the latter took against the stubborn republican opposition.

It was only after Pompeius had in this way procured for himself at the beginning of 702 the undivided consulship and an influence in the capital thoroughly outweighing that of Caesar, and after all the men capable of arms in Italy had tendered their military oath to himself personally and in his name, that he formed the resolution to break as soon as possible formally with Caesar; and the design became distinctly enough apparent. That the judicial prosecution which took place after the tumult on the Appian Way lighted with unsparing severity precisely on the old democratic partisans of Caesar[12], might perhaps pass as a mere awkwardness. That the new law against electioneering intrigues, which had retrospective effect as far as 684, included also the dubious proceedings at Caesar's candidature for the consulship[13], might likewise be nothing more, although not a few Caesarians thought that they perceived in it a definite design. But people could no longer shut their eyes, however willing they might be to do so, when Pompeius did not select for his colleague in the consulship his former father-in-law Caesar, as was fitting in the circumstances of the case and was in many quarters demanded, but associated with himself a puppet wholly dependent on him in his new father-in-law Scipio[14]; and still less, when Pompeius at the same time got the governorship of the two Spains continued to him for five years more, that is to 709, and a considerable fixed sum appropriated from the state-chest for the payment of his troops, not only without stipulating for a like prolongation of command and a like grant of money to Caesar, but even while labouring ulteriorly to effect the recall of Caesar before the term formerly agreed on through the new regulations which were issued at the same time regarding the holding of the governorships.

These encroachments were unmistakeably calculated to undermine Caesar's position and eventually to overthrow him. The moment could not be more favourable. Caesar had conceded so much to Pompeius at Luca, only because Crassus and his Syrian army would necessarily, in the event of any rupture with Pompeius, be thrown into Caesar's scale; for upon Crassus - who since the times of Sulla had been at the deepest enmity with Pompeius and almost as long politically and personally allied with Caesar, and who from his peculiar character at all events, if he could not himself be king of Rome, would have been content with being the new king's banker - Caesar could always reckon, and could have no apprehension at all of seeing Crassus confronting him as an ally of his enemies. The catastrophe of June 701, by which army and general in Syria perished, was therefore a terribly severe blow also for Caesar. A few months later the national insurrection blazed up more violently than ever in Gaul, just when it had seemed completely subdued, and for the first time Caesar here encountered an equal opponent in the Arvernian king Vercingetorix. Once more fate had been working for Pompeius; Crassus was dead, all Gaul was in revolt, Pompeius was practically dictator of Rome and master of the senate. What might have happened, if he had now, instead of remotely intriguing against Caesar, summarily compelled the burgesses or the senate to recall Caesar at once from Gaul! But Pompeius never understood how to take advantage of fortune. He heralded the breach clearly enough; already in 702 his acts left no doubt about it, and in the spring of 703 he openly expressed his purpose of breaking with Caesar; but he did not break with him, and allowed the months to slip away unemployed.

But however Pompeius might delay, the crisis was incessantly urged on by the mere force of circumstances.

The impending war was not a struggle possibly between republic and monarchy - for that had been virtually decided years before - but a struggle between Pompeius and Caesar for the possession of the crown of Rome. But neither of the pretenders found his account in uttering the plain truth; he would have thereby driven all that very respectable portion of the burgesses, which desired the continuance of the republic and believed in its possibility, directly into the camp of his opponent. The old battle-cries raised by Gracchus and Drusus, Cinna and Sulla, used up and meaningless as they were, remained still good enough for watchwords in the struggle of the two generals contending for the sole rule; and, though for the moment both Pompeius and Caesar ranked themselves officially with the so-called popular party, it could not be for a moment doubtful that Caesar would inscribe on his banner the people and democratic progress, Pompeius the aristocracy and the legitimate constitution.