Julius Caesar is still remembered for winning a civil war and helping bring about the end of the Roman Republic, leaving a line of emperors in its place, but it’s quite possible that none of what Caesar did would’ve happened without the template for such actions being set 40 years earlier. At the time, when Caesar was in his teens, war was being waged both on the Italian peninsula and abroad, with domestic politics pitting the conservative, aristocratic optimates against the populist, reformist populares, and this tension ultimately escalated into an all-out war. One of the leading populares was Caesar’s uncle, Gaius Marius, a military visionary who had restructured the legions and extended the privileges of land ownership and citizenship to legionaries on condition of successful completion of a fixed term of service. In the late 2nd century BCE, Marius had waged a successful campaign against several Germanic tribes, and after earning eternal fame in the Eternal City, Marius was appointed a consul several times. In 88 BCE, he entered into conflict with his erstwhile protégé, the optimate Sulla, over command of the army to be dispatched against Mithridates VI of Pontus, a long-time enemy of Rome and its Greek allies.

Ironically, Marius’s reforms had made the legions fiercely loyal to their individual generals rather than the state, which allowed Sulla to march his army against Rome and force Marius into exile. With that, Rome’s first civil war was officially underway, but Sulla’s triumph proved short-lived. Just as Sulla departed for a campaign, Marius returned at the head of a scratch army of veterans and mercenaries, taking over the city and purging it of Sulla’s optimate supporters, and though Marius died in 86 BCE, his party remained in power.

After Sulla finished mopping up the last scraps of resistance, he intended to take back Rome for himself at the head of his legions. He landed in the south of Italy and fought his way up the peninsula, defeating the armies dispatched from Rome to stop him. Some legions, including Cinna’s, rose up in spontaneous revolt and went over to Sulla’s side, and Cinna was murdered by his own men in the uprising. Sulla entered Rome in 82 BCE, becoming the first and only man to attack and conquer both Rome and Athens, and upon his successful return to Rome, Sulla proclaimed himself Dictator, an all-powerful legislative authority which normally could be only vested in times of extraordinary crisis and never for more than a period of six months. Sulla’s supporters went on a rampage across Rome, and some of them disinterred Marius’s body and dismembered it before throwing the pieces into the Tiber River. Of course, the purge included murdering Marius’s most prominent supporters as well, all in an effort to allow Sulla to proclaim himself Dictator for life. In the process, Caesar was a natural target and went into exile, putting him on the path to one of history’s most legendary military careers.

Despite the fact that Marius’ achievements, both personally and as a leading statesman, far outweigh the vast majority of Rome’s emperors, Marius is not a well-known figure outside academic circles. However, it is not possible to understand the evolution of the Roman Empire, and in particular the triumph of the Imperial system, without an understanding of both the strengths and weaknesses of the Republican system that preceded it, and few people were more responsible for those strengths and weaknesses than Marius. Gaius Marius: The Life and Legacy of the General Who Reformed the Roman Army chronicles how Marius rose through the ranks, his reforms of the military, and his lasting legacy.