In the year 67 BC, the assembly of the people decreed on a proposal by one of the tribunes to grant extraordinary powers to Pompey for the purpose of cleansing the whole Mediterranean of pirates. To that end, he was provided with a fleet and an army and vested with a formal authority (imperium) that surpassed the authority of the various provincial governors. In fact, for a limited period, he became the sole ruler of all Roman territory outside Italy. The operations against the pirates were successful, and only one year later and again on a proposal by one of the tribunes, the assembly bestowed another extraordinary command with an imperium surpassing that of the governors on Pompey, this time to set the whole of the east, from Asia Minor to Judea, in order. His actions there led, as already mentioned, to the organization of new Roman provinces, such as Syria, that encompassed the remnants of the old Seleucid empire, and the submission of Judea. In 61 BC, Pompey returned to Italy and celebrated a splendid triumph in Rome. He was at the height of his fame and prestige, and it now seemed that the Roman Republic would pass into the hands of one man.
Pompey, however, had made a fatal mistake. After landing in Italy, he had disbanded most of his army with the promise of a speedy distribution of land among his veterans, and had himself gone off to Rome to bask in the glory of his victories. But the lesson to be learnt from Marius and Sulla was that an ambitious politician should keep his army at hand. Now, a majority of the senators seized the moment and refused to approve of Pompey’s arrangements in the east and to assign land for his veterans in Italy. Pompey had to look for other means to fulfill his promise to his troops, safeguard his legacy in the east, and preserve his political prestige. Again, the rich Marcus Crassus presented himself, together with a younger, extremely talented, and extremely ambitious politician, Gaius Julius Caesar, a man from an old but impoverished patrician family, who had politically sided with the party of Marius. In 60 BC Pompey, Crassus, and Caesar joined forces to have Caesar elected as consul for the following year in which he would push through the ratification of Pompey’s measures, including the grants of land for his veterans; as a proconsul in 58 BC, Caesar would have a province and an army and thus the chance of winning glory and prestige in his turn. Crassus came up with the money needed for the election campaign, and Caesar was chosen as expected. His consulate in 59 BC was spent fulfilling the promises and agreements that the three men had made the year before (the other consul, Caesar’s
Colleague, tried to obstruct his program but was completely ignored): Pompey got what he wanted, and Caesar himself received by vote of the assembly the proconsulate of both the province of Gaul in Italy north of the river Po and of wider Gaul beyond the Alps for a period of five years, starting in 58 BC.
In the end, Caesar would spend nine years, from 58 till 50 BC, in Gaul, systematically conquering the land from the Alps and the river Rhine in the east, to the ocean in the west. Meanwhile in Rome, tribunes of the people with the support of Caesar agitated against the senate and realized by law the free distribution of grain to the urban proletariat. Pompey tried more and more to play a mediating role between the agitated masses and his former friends in the senate. For the time being, he adhered to his alliance with Caesar and Crassus, and at a conference in 56 BC their alliance was even renewed. The three men agreed that Caesar would have again five years in Gaul, starting in 54 BC, to finish his “pacifying” work there, while Pompey and Crassus would hold the consulate together for a second time in 55 BC, after which both would receive a province and an army for their further pursuit of glory and prestige: Spain for Pompey and Syria for Crassus. So it happened, and in 54 BC Crassus departed for the east in the hope of winning as much military glory as his two colleagues already enjoyed by campaigning against the Parthians. His expedition, however, ended in the desert near Carrhae (Harran), where his army, encircled by the Parthian mounted archers, suffered a dreadful defeat and Crassus himself was killed. Pompey, who stayed in Rome and let Spain be governed by his legati or representatives, now politically moved to the side of the senate and came to see the popularis Caesar as his main political rival.
Riots in Rome between gangs that had connections either with Caesar or with the senate, so it was generally believed, hindered the orderly processes of government. The consular elections for 52 BC were therefore canceled by the senate, and Pompey was for that year to act as consul sine collega (“consul without a colleague”). Presumably, Pompey himself enjoyed such a role: seemingly above the conflicting parties, preserving law and order as a princeps, a “first man” in the state, in a near-monarchical position. It testifies to their political weakness that most senators were prepared to preserve the republic and with it their own privileged position by such quasi-monarchical means. To those senators belonged the former consul Marcus Tullius Cicero, the greatest orator and one of the most important writers and intellectuals of his time, author of various political and philosophical treatises, who called for concord among the orders (senators, knights, and the common people) with the aim of preserving the republic, a concord that he envisaged in a grand reconciliation presided over by a princeps. Others, however, were less conciliatory. Fearful of Caesar’s popularity with the populace in Rome and his army in Gaul, they demanded that he lay down his command as soon as his proconsulate ended on the 1st of January 49 BC and come to Rome as a private citizen. Pompey, whose prestige threatened to be outstripped by Caesar’s, supported that demand, thus joining in fact the optimates against Caesar.
On the 1st of January 49 BC, conflict broke out: the senate rejected Caesar’s proposal to leave him only two legions and the proconsulate, so that he could stand for the consulate for the next year. Instead, it ordered Pompey to organize the defense of the republic against the man who now formally acted against the law by keeping his troops and his provinces.
Caesar, who had been in the north of Italy near the southern border of his province, reacted at once by crossing the stream of the Rubicon (near Rimini), which separated his province from Italy. He advanced much more quickly than his opponents had anticipated, and most senators accompanied Pompey in moving to the Balkans, since in Italy they had hardly any Roman troops. Caesar occupied Rome, and then progressed to Spain where in a short campaign he defeated the Pompeian forces and returned to Italy. Pompey, meanwhile, had assembled an army in Greece. In 48 BC, Caesar crossed the Adriatic and at Farsalos in Thessaly the decisive battle was fought. Defeated, Pompey sought refuge in Egypt, where he was murdered on the orders of the king. Caesar went to Egypt and there sided with Cleopatra against her brother and installed her as sole monarch of the country. The next year, in North Africa, the last “republican” army was destroyed, and Caesar returned to Rome in triumph. In the winter and spring of 45 BC, he was again in Spain, and in a final battle defeated the last “Pompeian” army; then back again in Rome he was received with quasi-divine honors.