Gaius Cassius Longinus
Gaius Cassius Longinus spent his life fighting against what he saw as tyranny, only to be remembered for the act that made him infamous: driving a blade into Julius Caesar's chest on the 15th of March, 44 BC. He was not the most famous face in the conspiracy. That distinction fell to Marcus Brutus, his brother-in-law and co-leader. Yet by most accounts, Cassius was the one who made the plot happen. He recruited the killers, built the network, and held the cause together. His own life stretches far beyond a single day in Rome. He survived one of the worst military disasters in Roman history. He outsmarted an invading Parthian army. He converted to Epicurean philosophy in middle age and tried to reconcile his new beliefs with the decision to murder a dictator. And when the battle he hoped would vindicate everything finally went wrong, he ordered a servant to kill him, not knowing that Brutus had actually won the day. The questions this story raises are not simple: why did a man who believed in the pleasures of peace become the driving force behind Rome's most consequential political killing? And how did ancient history, a Florentine poet, and Shakespeare each decide what Cassius ultimately deserved?
Cassius came from gens Cassia, a Roman family that had been prominent in Rome since the 6th century BC. His earliest recorded act of defiance happened while he was still at school, when he quarreled with the son of the dictator Sulla. It was a preview of a lifetime spent pushing against power. He studied philosophy at Rhodes under Archelaus of Rhodes and became fluent in Greek, an education that would shape the intellectual arguments he made decades later to justify his most famous choice.
In 54 BC, Cassius joined Marcus Licinius Crassus in an eastern campaign against the Parthian Empire, serving as quaestor. The campaign turned catastrophic at the Battle of Carrhae in 53 BC, in northern Mesopotamia. Plutarch records that Crassus might have avoided the disaster by listening to Cassius, who advised against invading Parthia at all. When the Roman army collapsed, it was Cassius who led the surviving troops back into Syria and organized a functioning defence for the province. According to Dio, soldiers and officers alike, including Crassus himself, were willing to hand overall command to Cassius in the aftermath, an offer he refused. The Parthians reportedly saw him as equal to Crassus in authority and superior in ability.
His reputation grew sharper in 51 BC, when a Parthian army under prince Pacorus and general Osaces invaded Syria. Cassius kept his forces behind the walls of Antioch, the province's most important city, refusing to fight in the open. When the Parthians gave up the siege and turned to raiding the countryside, Cassius followed at a distance, harassing them until he could choose his moment. On the 7th of October, as the Parthians turned away from Antigonea to begin their journey home, a detachment of his army staged a false retreat and drew them into an ambush. His main forces closed around them. General Osaces died of his wounds, and the rest of the Parthian army withdrew across the Euphrates.
Cassius returned to Rome in 50 BC as the republic edged toward civil war between Caesar and Pompey. Elected tribune of the plebs for 49 BC, he sided with the Optimates, the conservative senatorial faction, even though his own brother Lucius supported Caesar. He left Italy shortly after Caesar crossed the Rubicon and joined Pompey in Greece, where he was given command of part of the fleet.
In 48 BC, Cassius led his ships to Sicily and attacked and burned a large part of Caesar's navy, then turned north to harass vessels off the Italian coast. When news came of Pompey's defeat at the Battle of Pharsalus, Cassius headed toward the Hellespont, hoping to ally with Pharnaces II, the king of Pontus. Caesar overtook him before he could reach Pharnaces, and Cassius surrendered unconditionally.
Caesar's response was unexpected. Rather than punishing the man who had just burned his ships, Caesar made Cassius a legate and gave him a role in the Alexandrian War, specifically against Pharnaces, the very king Cassius had hoped to join. Cassius declined to follow Caesar into the subsequent African campaign against Cato and Scipio. He retired to Rome, spent two years in office, and deepened his friendship with the orator and statesman Cicero. By 44 BC, he had been appointed praetor peregrinus with the promise of the Syrian province for the following year. What stung him was that his brother-in-law Brutus, his junior, had been made praetor urbanus, a position Cassius considered his due. That slight sits in the historical record as one of the personal grievances that sharpened his resolve.
Ancient sources describe Cassius as "the moving spirit" in the conspiracy, the man who won over the chief assassins to the cause. Brutus became the public face and their leader, but it was Cassius who built the coalition. According to some accounts, Cassius had wanted to kill Mark Antony at the same time as Caesar, a precaution that might have altered everything. Brutus overruled him.
On the 15th of March, 44 BC, Cassius urged on the conspirators and struck Caesar in the chest. The assassination succeeded. The political aftermath did not go as planned. Antony seized the moment, turned the Roman public against the killers, and held the city. Cicero's letters from that same year repeatedly lament that Rome had merely traded one form of domination for another, since the men he called the Liberators had not moved against Antony.
Cassius and Brutus fled east. By 43 BC, Cassius had assembled twelve legions in Syria, drawing on his reputation from the Parthian campaigns to pull together support from other governors in the region. The Senate, by then in open conflict with Antony, confirmed Cassius as governor of the province. When the rival general Dolabella attacked, he was betrayed by his own allies and took his own life. Cassius had enough strength to march on Egypt, but Brutus called for his help. Cassius joined him at Smyrna with most of his army, leaving his nephew to govern Syria.
In 43 BC, Cassius sacked Rhodes while Brutus did the same to Lycia. The two men's armies were proclaimed imperator together at Sardis the following year. They crossed the Hellespont, marched through Thrace, and took up a position near Philippi in Macedon. Gaius Julius Caesar Octavian, later known as Augustus, and Mark Antony arrived to face them.
Cassius wanted to starve the triumvirate's forces out by holding the high ground. Antony forced the question, pushing both sides into what became a pair of engagements known collectively as the Battle of Philippi. Brutus attacked Octavian's position and took his camp. Cassius was overrun by Antony and did not know what Brutus had accomplished. Believing the cause lost, he ordered his freeman Pindarus to help him die. Pindarus carried out the order and then fled. When Cassius's body was found, his head had been severed from his body. Brutus called him "the Last of the Romans" and buried him at Thassos.
Sometime between 48 and 45 BC, Cassius converted to the philosophical school founded by Epicurus. The scholar Arnaldo Momigliano called the conversion "a conspicuous date in the history of Roman Epicureanism." Epicurus taught withdrawal from political life, yet prominent Romans found ways to reconcile that teaching with public careers. Calpurnius Piso Caesoninus, Caesar's father-in-law, was one such figure.
Cassius left a letter to Cicero that survives, in which he argued that goodness and clemency grow from love, and that cruelty grows from hatred. He quoted Epicurus directly: "there is no living pleasantly without living a good and just life." For Cassius, the philosophy was not a reason to stand aside. It was a reason to act. Momigliano traced a shift in his thinking from an early Epicurean orthodoxy, which valued detachment, to what he called a "heroic Epicureanism," in which virtue was something active rather than passive.
David Sedley observed that Brutus and Cassius were probably among the most publicly prominent philosophers of the ancient world, and that this was often not widely recognized. The question of whether Cassius's Epicurean beliefs actually drove the assassination, or merely provided a framework he used after the fact to explain a decision rooted in personal grievance and political calculation, is one scholars have not resolved. Miriam Griffin argued that his intellectual pursuits, like those of many Romans, may have been entirely separate from his political actions. Sedley himself found it unlikely that Epicureanism was sufficient as a primary motivation for violence against the dictator.
What the conversion did affect was the longer arc of history. During the Imperial period that followed, Stoicism became the philosophy of opposition, not Epicureanism. Momigliano argued that this shift helps explain why later historians found Cassius harder to understand than Brutus, and judged him less admirable.
In Canto XXXIV of Dante's Inferno, Cassius occupies one of three mouths of Satan at the very centre of Hell, being chewed for eternity as punishment for killing Julius Caesar. The other two sharing that fate are Brutus and Judas Iscariot. Dante's construction equated the betrayal of Caesar with the betrayal of Christ, placing political murder on the same level as religious treachery. Dante did not extend the same treatment to Decimus Brutus, the third major figure in the conspiracy, and the reason for that omission remains unknown.
Shakespeare drew a different Cassius in his play Julius Caesar, citing the speech at Act I, scene ii, lines 190-195, in which Caesar himself delivers the warning: "Yond Cassius has a lean and hungry look; He thinks too much: such men are dangerous." In the play's final scenes, Cassius tells a subordinate that the day is the 3rd of October and his birthday, and dies shortly afterward. Shakespeare tied his death to his birth date, a detail that makes the ending feel like a closed circle.
The two portraits, Dante's eternally punished traitor and Shakespeare's brooding, dangerous schemer, have shaped how Cassius has been read for centuries. Both chose to foreground the assassination at the expense of Carrhae, Syria, and the Epicurean correspondence. Cassius's own letter to Cicero, with its argument about cruelty, love, and the conditions for a pleasant life, offers a version of the man that neither poet quite reached.
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Common questions
Who was Gaius Cassius Longinus and what is he known for?
Gaius Cassius Longinus was a Roman senator and general who lived from around 86 BC to the 3rd of October, 42 BC. He is best known as the leading instigator of the plot to assassinate Julius Caesar on the 15th of March, 44 BC, and is described in ancient sources as the moving spirit of the conspiracy.
How did Gaius Cassius Longinus die?
Cassius died by suicide after being defeated by Mark Antony at the Battle of Philippi in 42 BC. Unaware that his co-commander Brutus had won against Octavian the same day, he ordered his freeman Pindarus to help him die. Brutus mourned him as the Last of the Romans and buried him at Thassos.
What role did Cassius play in the Battle of Carrhae?
Cassius served as quaestor under Marcus Licinius Crassus in the eastern campaign that led to the Battle of Carrhae in 53 BC. When the Roman army was crushed in what was considered the worst Roman defeat since Cannae in 216 BC, Cassius led the surviving troops back into Syria and organized the province's defence. Plutarch recorded that Crassus might have avoided the disaster by following Cassius's advice not to invade Parthia.
What was Cassius's philosophical belief and how did it relate to the assassination of Caesar?
Cassius converted to Epicureanism sometime between 48 and 45 BC, a school of thought founded by Epicurus. Arnaldo Momigliano called this conversion a conspicuous date in the history of Roman Epicureanism and argued that Cassius used it not to enjoy private pleasures but to provide a philosophical justification for killing a tyrant. Scholars debate whether his beliefs actually motivated the assassination or merely offered a post-hoc framework for a decision driven by personal grievance and politics.
How does Cassius appear in Dante's Inferno?
In Canto XXXIV of Dante's Inferno, Cassius is placed at the very centre of Hell, being chewed in one of the three mouths of Satan for eternity as punishment for killing Julius Caesar. He shares this fate with Brutus and Judas Iscariot, placing his betrayal of Caesar on the same moral level as Judas's betrayal of Jesus.
How is Cassius portrayed in Shakespeare's Julius Caesar?
In Shakespeare's Julius Caesar, Cassius is a major figure as the leader of the conspiracy to assassinate Caesar. Caesar distrusts him and warns that Cassius has a lean and hungry look and thinks too much, calling such men dangerous. In the play's final scenes, Cassius tells a subordinate that the 3rd of October is his birthday, and he dies shortly afterward.
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30 references cited across the entry
- 3Life of CaesarPlutarch
- 4De Vita CaesarumSuetonius — 121
- 18BookPompey, Cato, and the Governance of the Roman EmpireKit Morrell — Oxford University Press — 2017