What was The Conspiracy of Catiline?

The failed treason plot of Lucius Sergius Catilina

Cicero accuses Catiline
Cicero accuses Catiline. Public Domain.

During the time of Caesar and Cicero, in the final decades of the Roman Republic, a group of debt-ridden aristocrats, led by the patrician Lucius Sergius Catilina (Catiline), conspired against Rome. Catiline had been thwarted in his ambitions for the top political post of consul, and charged with abuse of power while serving as governor. He gathered into his conspiracy Etruscans and disaffected senators and equestrians. With these, he raised an army.

Catiline's plan failed.

The Conspiracy Revealed

On the night of 18 October, 63 B.C., Crassus brought letters to Cicero warning of a plot against Rome that was led by Catiline. This plot came to be known as the Catilinarian Conspiracy.

The Senate is Alarmed

The following day, Cicero, who was consul, read the letters in the Senate. The Senate ordered further investigation and on the 21st, passed the Senatus Consultum Ultimum 'final resolution of the senate'. This gave absolute imperium 'power' to the consuls and created a state of martial law.

The Conspirators Stir up the Countryside

News arrived that enslaved people were revolting in Capua in Campania and Apulia. There was panic in Rome. Praetors were instructed to raise troops. Throughout these events, Catiline remained in Rome; his allies stirring up the trouble in the countryside. But on the 6 of November Catiline announced plans to leave the city to take control of the revolt.

When Cicero started delivering a series of inflammatory speeches against Catiline, the conspirators planned to retaliate by having a tribune stir up the people against Cicero and his unjust accusations. Fires were to be set, and Cicero was to be assassinated.

Ambushing the Conspirators

Meanwhile, the conspirators had approached the Allobroges, a tribe of Gauls. The Allobroges thought better of allying themselves with the Roman traitors and reported the proposal and other details of the conspiracy to their Roman patron, who, in turn, reported to Cicero. The Allobroges were instructed to pretend to go along with the conspirators.

Cicero arranged for troops to ambush the conspirators with the envoys (false allies) at the Milvian Bridge.

Pater Patriae

The conspirators who were caught were executed without trial in December 63. For these summary executions, Cicero was honored, hailed as savior of his country (pater patriae).

The Senate then mobilized troops to face Catiline at Pistoria, where Catiline was killed, thereby ending the Conspiracy of Catiline.


Cicero produced four orations against Catiline that are considered some of his best rhetorical pieces. He had been supported in the decision to execute by other senators, including the strict moralist and enemy of Caesar, Cato. Since the Senatus Consultum Ultimum had been passed, Cicero technically held the power to do whatever was necessary, including execute, but likewise, he was the one responsible for the deaths of Roman citizens.

Later, Cicero paid a high price for what he did to save the country. Another enemy of Cicero, Publius Clodius, pushed through a law that prosecuted Romans who executed other Romans without trial. The law was clearly designed to give Clodius a way of bringing Cicero to trial. Instead of facing trial, Cicero went into exile.