Caesar Crosses The Rubicon – 10 January 49 BC

“The die is cast.”

Caesar Crosses The Rubicon10 January 49 BC By the middle of the first century BC, the Roman Republic was swiftly disintegrating. The turn of the century had seen Gaius Marius end the threat of the Cimbri invasion following a series of military reverses by abandoning the land requirements for the legions.

While it swelled the military ranks, it ensured soldiers would be more loyal to their general than the state, relying on their leader for pay and booty. Political polarization saw the Populare (populist) party being headed by Marius, and the Optimate (conservative) faction led by his former adjutant Lucius Cornelius Sulla, who took the took the unthinkable measure of marching on Rome as disagreement between the two factions escalated into civil war.

There was a period of calm after Sulla renounced his dictatorship, with the two leading powers establishing themselves the two Sulla supports Pompey Magnus, son of Social War general Pompey Strabo, a (relatively) recently Romanised Gaul who owned much of Cisalpine Gaul (northern Italy), and Marcus Crassus, the richest man in the republic who swelled his purse from the proscriptions of Sulla. It looked as if the two may come to blows when both had legions outside Rome following the Spartacus revolt, though mediating between them to form a triumvirate to control the state was a third individual – the nephew of Marius, Gaius Julius Caesar.

Map of Roman Empire (1st century BC) CC BY-SA 3.0

The Sicilian Wars

While Pompey gained glory leading a grand expedition east, ostensibly against Mithridates of Pontus but ultimately marching to the Caspian Sea, dissolving the Seleucid Empire and annexing the Levant, Crassus grew as wealthy as the state itself. After a shared consulship of the two, Caesar’s consulship saw him entire Gaul and wage a decade-long war that would bring the province under Roman control and lead the first forays to Britannia. Their alliance broke down as Crassus died at Carrhae leading a doomed expedition into Persia, while Caesar’s daughter, who was married to Pompey, died in childbirth. As the war concluded Caesar based himself in northern Italy, looking to run for the Consulship in absentia which, while uncommon, was not unprecedented. He could legally stand for the office given it was a decade since he last stood, and it would grant him immunity from prosecution with his enemies circling and looking to hold him accountable for numerous crimes and slights against them.

When Pompey fell ill and then recovered to jubilant celebrations, he took this as a sign of his supremacy over Caesar. Rome was faced with both men maintaining legions, and while Pompey’s were in the city itself following recent unrest, the boni (“good men”) faction of the Senate (including Cato and Bibilus) aligned themselves with Pompey, against Caesar. The Senate demanded Caesar disband his legions, though the Populares proposed both men should do so simultaneously. Furthermore, the Senate refused to back this, and only the vetoes of Marc Antony and Curio prevented Caesar being declared a public enemy.

The Senate voted to enable Pompey to raise 130,000 men and go north to check Caesar, who they believed would take some time to assemble his Gallic legions to complement the Thirteenth Legion with which he had wintered at Ravenna.

Seizing the initiative, Caesar crossed the Rubicon, a tributary of the River Po, on 10 January 49 BC with just the Thirteenth Legion.

After having a vision of his success the night before, the regular gambler Caesar famously quoted the Greek playwright Menander as he crossed the river, declaring “the die is cast”. So began the great civil war that would bring to an end the Roman Republic. Towns and garrisons defected to Caesar as he marched, and while Pompey looked top recruit in Campania, the panicked senators fled to his entourage without even bothering to empty the treasury.

Enemy At The Gates

With the Italian situation looking grim, Pompey decided to flee to Greece. This would spare Italy the horrors only so recently inflicted by the Social War, while also seeing Caesar pincered between Pompey’s power base in the east and his legions in Hispania. Pompey landed at Dyrrachium and swiftly began raising legions from his veterans in the region, while his eastern vassals promised reinforcements in their tens of thousands. A vast fleet assembled under Bibulus promised to prevent Caesar from crossing the Adriatic. For his part, Caesar led a stunning 27-day march into Hispania, routing Pompey’s veteran legions that outnumbered him two-to-one at the Battle of Ilerda. Eleven days as dictator in Rome saw a skeletal Senate vote him Consul, allowing him to slip the blockade and cross the Adriatic in winter. Caesar was initially defeated at Dyrrachium, though when Pompey gave chase to the Greek interior he won a stunning victory at Pharsalus. 

This would be followed by a campaign in Egypt to install Cleopatra on the throne, a victory against Pontus as Zela so swift that Caesar declared “Veni. Vidi. Vici.” (“I came. I saw. I conquered.”), and then further campaigns against the remaining opposition Senators at Thapsus and Munda.

The unravelling of the republic would not end with Caesar’s assassination, for his adjutant Antony and his posthumously adopted son (his great nephew) Octavian would first fight one another at Mutina, then the remaining republican leaders at Philippi, and finally each other again at Actium to leave Octavian styling himself as Augustus as the republic morphed into the empire. The 17 years of fighting after Caesar crossed the Rubicon saw 420,000 Italians fighting in one of antiquity’s bloodiest periods, and a transition that saw Rome become an empire.


Caesar Crosses The Rubicon10 January 49 BC Written by Jack Tappin


Caesar Crosses The Rubicon10 January 49 BC Written by Jack Tappin

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