Alea iacta est. The die is cast. Rome’s Senate created an ultimatum for Caesar. That decision led to a civil war. But who’s decision was more culpable? The Senate for setting the stage for war? Or Caesar for stepping on the scene?

While Julius Caesar had six months left on his term as governor of Gaul and Illyricum (modern: France, Belgium, Switzerland, Southern Netherlands, Western Germany, Northern Italy, Croatia, Montenegro, Albania) in 50 B.C., he attempted to run for the elected position of consul back in Rome. Rome had two annually elected consuls. They served like co-presidents, presiding over Rome and its Senate.

Caesar’s effort to become a consul was thwarted by a small but powerful faction of Caesar’s political rivals back in Rome led by his old friend, Gnaeus Pompeius. More than just challenge Caesar’s right to run on the grounds that Caesar was not physically present in Rome, Pompey managed to convince the Senate that Caesar should contribute a legion for an upcoming war in the East.

Caesar did so, contributing two legions because he had borrowed one legion from Pompey during his campaign in Gaul. These two legions, in turn, were taken by Pompey though no war in the East was launched. Rather, it was against Caesar that war would be waged.

Pompey had long been trying to assert his sole dominance over Rome’s Senate. Through bribery and lavish gifts of largess, he was gaining influence in Rome and putting his friends and personal subordinates in places of power. To wit, Caesar felt wronged by all this. The two men had been close allies in forming the First Triumvirate along with Marcus Crassus–whose sons had been with Caesar in Gaul–an informal, three-way alliance used to surpass Rome’s Senate and acquire more individual power than otherwise possible in the city’s republican system.

Rome was split between Pompey and Caesar. Pompey pronounced that any Roman not in favor of Pompey was in favor of Caesar. Pompey mainly had the support of the Senate majority and the patricians, the upper class.

Caesar was a man of the people, the plebeians, a self-proclaimed democrat. They loved Caesar because he brought power and glory to Rome. The Roman people liked that Caesar was acquiring new lands and conquering Gaul for them. His military endeavors were creating economic opportunities for Romans as trading colonies were being founded in Gaul and a soldier would not only be less likely to die under Caesar’s command but could also have his hand at some booty. And Caesar’s feats of victorious conquest fell in line with the cherished Roman virtue of virtus, or man’s pursuit of money, power, and glory for the sake of his city-state.

A democratic election by the citizens of Rome would have gone Caesar’s way. A decision by the Senate Republic would have likely favored Pompey. Thus, Rome was divided.

Once Caesar’s term as governor in Gaul was up he was told by the Senate to disband his armies before returning to Rome in January 49 B.C. The deadline was the Rubicon River, the border of Cisalpine Gaul (modern: Northern Italy) and Italia. He did not do so.

Crossing the Rubicon was the famed act, which coined the idiom, that marked Caesar’s intent to fight for his right to run for consul and pursue the power he had grown hungry for in Gaul. It was a point of no return. He crossed the line. War would break out.

Source: Caesar. Civil War. Edited and translated by Cynthia Damon. Loeb Classical Library 39. Cambridge, MA: Harvard University Press, 2016.

Purchase Source: Caesar: Civil War (Loeb Classical Library)