The Romans did not lose wars. In fact, the Middle and Late Republic are periods of almost continuous Roman success; yes, they lost battles, but they nearly always won the war. Despite this success, military campaigns still had the potential to be disruptive to political life at home. The resources devoted to them and the political divisiveness they caused wore away notions of the common good, political solidarity, and social trust. Thus, Sulla and Marius viewed the war against Mithridates, who had orchestrated the murder of thousands of Romans and Italians, not only as the serious threat to Rome it was, but also as an opportunity for personal aggrandizement; the consequences of their ambition and violence were devastating for Rome and thousands of its citizens who died in the resulting strife. Later conflicts had similar impacts.

In 60 BCE, Rome's three most powerful, richest, and ambitious men, Pompey, Crassus, and Caesar, decided to form a political alliance, which historians call the First Triumvirate. Pompey was the most successful militarily and the richest. He had strung together a number of unprecedented offices and military commands throughout the 70s and 60s BCE. The first elected office he ever held was the consulship, a violation of Roman custom; he also held sweeping commands against the Mediterranean pirates and concluded the protracted war against Mithridates, expanding Rome's empire into the Eastern Mediterranean. The commands, which he executed efficiently and effectively, granted him immense power; his authority against the pirates troubled senators because he did not have a colleague in the office, an unrepublican precedent. His career would later serve as a model for Augustus, Rome's first emperor.

Caesar's career was on the rise, and though he had been a successful military commander, he did not yet have a distinctive military achievement to rival Pompey; in addition, he was indebted to men like Crassus. Crassus, a wealthy slum lord, was infamous for his remark that a man was not rich unless he had the money to buy an army. Though powerful and wealthy, he barely had any military success, save suppressing the revolt of Spartacus, from the Roman perspective hardly the stuff to win a proper triumph. Crassus and Caesar were zealous for military triumphs that would give them the same distinction as Pompey and the plunder that would come with it.