Ancient Rome · January 49 BCE
Why Did Caesar Cross the Rubicon?
In short
- In January 49 BCE Caesar led his army across the Rubicon into Italy, starting a civil war.
- He acted because giving up his army meant prosecution by enemies who controlled the Senate.
- Caesar beat Pompey and his allies between 48 and 45 BCE, using speed and clemency.
One night in January 49 BCE, Julius Caesar slipped away from a dinner party in Ravenna, borrowed mules from a nearby bakery and got lost in the dark. By morning he had caught up with his troops at a small river. On one bank he was a governor with an army; on the other, the same army made him a rebel.
Why a river mattered
The Rubicon was a small stream near the Adriatic coast, but it marked the border between Caesar's province of Cisalpine Gaul and Italy itself. A governor's command ended at his province's edge; leading troops across it without the Senate's authority was treason.
On 7 January the Senate had passed its emergency decree against Caesar, the same “final decree” first used against Gaius Gracchus. Two tribunes who supported him, Mark Antony and Quintus Cassius, fled Rome disguised as slaves. Caesar now had a cause to show his soldiers: the sacred rights of the tribunes had been trampled.
Three men and a broken alliance
Caesar's rise rested on a private pact made around 60 BCE with Rome's most famous general, Pompey, and its richest man, Crassus. It won Caesar a consulship in 59 BCE and then command in Gaul, where nearly a decade of war brought him vast wealth and an army devoted to him. Plutarch claims a million people were killed and another million enslaved; the figures may be inflated, but the scale was enormous.
The alliance came apart. Pompey's wife Julia, Caesar's daughter, died in 54 BCE; Crassus was killed fighting the Parthians at Carrhae in 53. Pompey drifted toward Caesar's enemies in the Senate.
Prosecution or power
Caesar wanted to move straight from his command into a second consulship, which would keep him immune from prosecution. His enemies, led by Cato the Younger, insisted he give up his army first, and Cato had promised to put him on trial the moment he did. In December 50 BCE the Senate voted 370 to 22 that Caesar and Pompey should both give up their commands, but Caesar's opponents ignored the vote.
Suetonius, citing an eyewitness, records what Caesar said later as he looked over the dead after his victory at Pharsalus: “They would have it so. Even I, Gaius Caesar, after so many great deeds, should have been found guilty, if I had not turned to my army for help.”
The die is cast
What happened at the river comes to us from later writers. Suetonius, writing about 170 years afterwards, says Caesar hesitated, then said: “The die is cast.” Plutarch says he spoke the words in Greek, a line from the comic playwright Menander. Caesar's own history of the war does not mention the Rubicon at all.
He crossed with a single legion. Pompey had once boasted that he had only to stamp his foot anywhere in Italy for armies to spring up; now a senator told him to start stamping. Pompey abandoned Rome, and then Italy.
A war across the Mediterranean
Caesar combined speed with mercy. When enemy troops surrendered at Corfinium, he let their commanders go free, a policy of clemency that won over waverers. He defeated Pompey at Pharsalus in Greece in 48 BCE. Pompey fled to Egypt, where courtiers of the boy king Ptolemy XIII had him killed as he came ashore.
Caesar followed, became entangled in Egypt's royal feud and sided with Cleopatra. Victories at Thapsus in 46 BCE and Munda in 45 ended organised resistance. Cato killed himself rather than accept Caesar's pardon. Caesar was master of the Roman world.
In their own words
“Let us go where the signs of the gods and the injustice of our enemies call us. The die is cast.”
Suetonius, Life of the Deified Julius 32, c. 121 CE
Suetonius gives the words in Latin (iacta alea est). Plutarch (Pompey 60, Caesar 32) says Caesar spoke the phrase in Greek, “let the die be cast”, a line from the playwright Menander. Caesar's own Civil War does not mention the crossing.
Why it happened
- Caesar faced prosecution if he gave up his command and became a private citizen.
- The alliance with Pompey collapsed after Julia's death in 54 BCE and Crassus's in 53 BCE.
- Caesar's enemies in the Senate refused compromise and passed the emergency decree against him.
- Caesar's legions, enriched by Gaul, were loyal to him personally.
What happened next
- A four-year civil war ended with Caesar as dictator. Read the story →
- Pompey was murdered in Egypt, and Caesar's alliance with Cleopatra began. Read the story →
- Caesar pardoned many enemies, including Brutus and Cassius, who would later conspire against him. Read the story →
Why it still matters
Caesar's dilemma, to give up power and risk prosecution or keep it by force, is one political scientists still study: leaders who expect to be tried after leaving office have every reason to cling on. When Chile's Augusto Pinochet stepped down as army chief in 1998, he moved straight into a lifetime Senate seat, provided for in the constitution his regime had written, which carried immunity from prosecution.
Key people
- Julius Caesar
- Governor of Gaul who invaded Italy in 49 BCE and won the civil war
- Pompey the Great
- Rome's leading general, Caesar's ally and son-in-law, then his opponent
- Marcus Licinius Crassus
- Rome's richest man and third partner in the alliance, killed at Carrhae in 53 BCE
- Cato the Younger
- Leader of Caesar's opponents in the Senate; killed himself in 46 BCE
- Cleopatra VII
- Queen of Egypt who allied with Caesar in 48–47 BCE
Key terms
- Cisalpine Gaul
- “Gaul this side of the Alps”: northern Italy, then governed as a province whose southern border was the Rubicon.
- First Triumvirate
- Modern name for the informal alliance of Caesar, Pompey and Crassus from about 60 BCE; it had no legal standing.
- Clemency (clementia)
- Caesar's policy of pardoning defeated enemies; it won supporters but also implied he had the power to pardon.
- Crossing the Rubicon
- A phrase meaning to pass a point of no return.
Test yourself
Caesar's own account of the civil war describes his crossing of the Rubicon.
- True
- False
Show the answer
False. Caesar's Civil War moves from his speech to the troops at Ravenna straight to his arrival at Ariminum (Rimini). The river and the famous words come from Suetonius and Plutarch, writing more than 150 years later.
The full lesson in the app ends with 5 questions like this one.
Connected stories
- Marius, Sulla and the Army That Changed Rome: Sulla's march on Rome in 88 BCE was the precedent for Caesar's.
- The Gracchi and the Crisis of the Republic: The Senate's emergency decree, first used against Gaius Gracchus, was turned against Caesar.
- Cleopatra: The Last Queen of Egypt: Chasing Pompey to Egypt drew Caesar into Cleopatra's fight for her throne.
- The Ides of March: Victory made Caesar dictator, and made him a target.
Frequently asked questions
Why did Julius Caesar cross the Rubicon?
Caesar faced prosecution if he gave up his command and became a private citizen. The alliance with Pompey collapsed after Julia's death in 54 BCE and Crassus's in 53 BCE. Caesar's enemies in the Senate refused compromise and passed the emergency decree against him. Caesar's legions, enriched by Gaul, were loyal to him personally.
What happened after Caesar crossed the Rubicon?
A four-year civil war ended with Caesar as dictator. Pompey was murdered in Egypt, and Caesar's alliance with Cleopatra began. Caesar pardoned many enemies, including Brutus and Cassius, who would later conspire against him.
Why did Caesar refuse to give up his army in 49 BCE?
As a private citizen he faced prosecution by his enemies. Holding office gave Caesar immunity. His enemies, led by Cato, planned to prosecute him as soon as he became a private citizen, so he tried to pass directly from his command to a second consulship.
What is the main primary source for “Caesar Crosses the Rubicon”?
Suetonius, Life of the Deified Julius 32 (c. 121 CE). Suetonius gives the words in Latin (iacta alea est). Plutarch (Pompey 60, Caesar 32) says Caesar spoke the phrase in Greek, “let the die be cast”, a line from the playwright Menander. Caesar's own Civil War does not mention the crossing.
Sources
- Suetonius, Life of the Deified Julius 29–35
- Plutarch, Lives of Caesar (28–35) and Pompey (57–60)
- Tom Holland, Rubicon (2003)
- Adrian Goldsworthy, Caesar: Life of a Colossus (2006)
Images are credited under each picture. Paintings and photographs come from public collections via Wikimedia Commons; scenes with no surviving image are marked as illustrations.
