Battles & Wars › Greece, Rome & Han › Roman Empire
Caesar's Civil War: the Rubicon and Pharsalus
49–45 BC; Rubicon January 49 BC; Pharsalus August 9, 48 BC· War· Europe
Well documentedSolid records, physical evidence or scientific consensus.
War of 49–45 BC in which Julius Caesar defeated Pompey and the Senate's forces and made himself master of Rome.
See it on the Battles & Wars map →What happened
Ordered to give up his army, Caesar crossed the Rubicon, the stream marking his province's border, into Italy with one legion in January 49 BC, reportedly saying 'the die is cast'. Pompey and much of the Senate fled to Greece. At Pharsalus on August 9, 48 BC, about 22,000 of Caesar's veterans beat roughly 45,000 under Pompey, by Caesar's figures. Pompey fled to Egypt and was murdered there. Caesar then won in Africa (Thapsus, 46 BC) and Spain (Munda, 45 BC).
Why it matters
It ended the Republic in practice: Caesar became dictator for life in 44 BC, and his murder that year led to new civil wars won by his heir Octavian, Rome's first emperor.
How we know
Caesar's own Civil War commentaries, letters Cicero wrote during the events, and later histories by Plutarch, Appian, Suetonius and Cassius Dio.
Still debated
Army sizes at Pharsalus rest on Caesar's own, possibly self-serving, figures, and whether he really said 'the die is cast', and in Greek or Latin, is debated.
Connections (4)
▸Julius Caesar launched and won Caesar's Civil War: the Rubicon and PharsalusWell documented
The connection
Caesar's enemies in the Senate ordered him to give up his army before he could stand for a second consulship, which would expose him to prosecution. Rather than submit, he led troops across the Rubicon into Italy, an act of war. He then beat Pompey's side across the Mediterranean in four years.
When and how
The Rubicon in northern Italy, January 10 or 11, 49 BC, through to Munda in southern Spain, March 45 BC.
How we know
Caesar's own Civil War commentaries and Cicero's letters written at the time; Suetonius and Plutarch later describe the crossing.
Debates and open questions
Who was more to blame, Caesar or his Senate opponents, has been argued since ancient times, and the legal end date of his command is unclear.
▸Gallic Wars gave Caesar the loyal army he used in Caesar's Civil War: the Rubicon and PharsalusWell documented
The connection
Eight years of fighting in Gaul gave Caesar veteran legions, loyal to him personally for pay, plunder and the promise of land, and huge wealth from loot and slaves. That army and money let him defy the Senate in 49 BC and beat Pompey's larger but less seasoned forces.
When and how
Gaul, 58–50 BC, then Italy, Spain and Greece from 49 BC; legions such as the famous Tenth followed him throughout.
How we know
Caesar's commentaries, Suetonius and Plutarch describe the legions' loyalty, and ancient writers stress how Gallic plunder funded his politics.
Debates and open questions
Ancient figures for Gallic losses (Plutarch: a million killed and a million enslaved) are probably exaggerated, and how much the war enriched Caesar can only be estimated.
▸Caesar's Civil War: the Rubicon and Pharsalus doomed the Republic, paving the way for Roman EmpireWell documented
The connection
Victory made Caesar dictator for life, ending the Republic's shared rule in practice. His murder in 44 BC set off new civil wars. His adopted heir Octavian won them, defeating Antony and Cleopatra at Actium in 31 BC, and in 27 BC became Augustus, the first emperor.
When and how
Rome and its provinces, 49–27 BC; Caesar, his assassins Brutus and Cassius, Mark Antony and Octavian.
How we know
Ancient historians from Suetonius to Cassius Dio, along with coins and inscriptions, record the shift from Republic to one-man rule.
Debates and open questions
Whether the Republic was already doomed by a century of crises, from the Gracchi to Sulla, or whether Caesar personally broke it, is a classic debate.
▸Battle of Carrhae killed Crassus, breaking the alliance before Caesar's Civil War: the Rubicon and PharsalusWell documented
The connection
Crassus, Caesar and Pompey had shared power informally since about 60 BC, the so-called First Triumvirate. Crassus's death at Carrhae, a year after Caesar's daughter Julia, Pompey's wife, died, left two rivals with no third partner or family tie to balance them. Pompey drifted to the Senate's side, and war came in 49 BC.
When and how
Carrhae (Harran, southeastern Turkey), 53 BC; the three men had renewed their pact at Luca in 56 BC.
How we know
Ancient writers including Plutarch and the poet Lucan explicitly saw Crassus's death as removing the balance between Caesar and Pompey.
Debates and open questions
Modern historians debate how much Crassus's death mattered compared with Julia's death and politics in Rome; war may have come anyway.