Running for the consulship for a second time after having lost the first time, Catiline was an advocate for the poor, calling for the cancellation of debts and land redistribution. Cicero, in indignation, issued a law prohibiting machinations of this kind. It was obvious to all that the law was directed specifically at Catiline. Catiline, in turn, conspired to murder Cicero and the key men of the Senate on the day of the election in what became known as the second Catilinarian conspiracy. Cicero discovered the plan and postponed the election to give the Senate time to discuss the attempted coup d'état.
The day after the election was supposed to be held, Cicero addressed the Senate on the matter and Catiline's reaction was immediate and violent. In response to Catiline's behavior, the Senate issued a senatus consultum ultimum, a kind of declaration of martial law invoked whenever the Senate and the Roman Republic were considered to be in imminent danger from treason or sedition. Ordinary law was suspended and Cicero, as consul, was invested with absolute power.
When the election was finally held, Catiline lost again. Anticipating the bad news, the conspirators had already begun to assemble an army, made up mostly of Sulla's veteran soldiers. The nucleus of conspirators was also joined by some senators. The plan was to initiate an insurrection in all of Italy, put Rome to the torch and to kill as many senators as they could.
Through his own investigations, Cicero was aware of the conspiracy. On November 8, Cicero called for a meeting of the Senate in the Temple of Jupiter Stator near the forum, which was used for this purpose only when great danger was imminent. Catiline attended as well. It was in this context that Cicero delivered one of his most famous orations.
Oratio in Catilinam Prima in Senatu Habita
As political orations go, this was relatively short—some 3,400 words—and to the point. The opening remarks are still widely remembered and used after 2,000 years:
Quo usque tandem abutere, Catilina, patientia nostra? Quam diu etiam furor iste tuus nos eludet? Quem ad finem sese effrenata iactabit audacia? How long, O Catiline, will you abuse our patience? And for how long will that madness of yours mock us? To what end will your unbridled audacity hurl itself?
Also remembered is the famous exasperated exclamation, O tempora, o mores! (Oh the times! Oh the customs!)
Catiline was present when this speech was delivered. When he arrived at the Temple of Jupiter Stator and took his seat, however, the other senators moved away from him leaving him alone in his bench. Catiline tried to reply after the speech, but senators repeatedly interrupted him, calling him a traitor. He ran from the temple, hurling threats at the Senate. Later he left the city and, though he claimed that he was placing himself in self-imposed exile at Marseilles, he in fact went to the camp of Manlius, who was in charge of the army of rebels. The next morning Cicero assembled the people, and gave a further oration.
Oratio in Catilinam Secunda Habita ad Populum
In this speech, Cicero informed the citizens of Rome that Catiline had left the city, not in exile (as it was rumored), but to join with his illegal army. He described the conspirators as rich men who were in debt, men eager for power and wealth, Sulla's veterans, ruined men who hoped for any change, criminals, profligates, and other men of Catiline's ilk. He assured the people of Rome that they had nothing to fear because he, the consul, and the gods would protect the state.
Meanwhile, Catiline joined up with Gaius Manlius, commander of the rebel force. When the Senate was informed of these developments, they declared the two of them public enemies. Antonius Hybrida (Cicero's fellow consul), with troops loyal to Rome, followed Catiline while Cicero remained at home to guard the city.
Oratio in Catilinam Tertia ad Populum
In this speech, Cicero claims that the city should rejoice because it has been saved from a bloody rebellion. He presents evidence that all of Catiline's accomplices confessed to their crimes. He asked for nothing for himself but the grateful remembrance of the city, and acknowledged that this victory was more difficult than one in foreign lands because the enemies were citizens of Rome.
Oratio in Catilinam Quarta in Senatu Habita
In his fourth and final argument, which took place in the Temple of Concordia, Cicero establishes a basis for other orators (primarily Cato) to argue for the execution of the conspirators. As consul, Cicero was formally not allowed to voice any opinion in the matter, but he circumvented the rule with subtle oratory. Although very little is known about the actual debate (except for Cicero's argument, which has probably been altered from its original), the Senate majority probably opposed the death sentence for various reasons, one of which was the nobility of the accused. For example, Julius Caesar argued that exile and disenfranchisement would be sufficient punishment for the conspirators, and one of the accused, Lentulus, was a praetor. However, after the combined efforts of Cicero and Cato, the vote shifted in favor of execution, and the sentence was carried out shortly afterwards.
While most historians agree that Cicero's actions, and in particular the final speeches before the Senate, saved the republic, they also reflect his self-aggrandisement—and to a certain extent envy—probably born out of the fact that he was considered a novus homo, a Roman citizen without noble or ancient lineage.