Defeated in his immediate object, Catilina began to entertain the idea of carrying out his designs by force. The time was eminently favourable for an armed insurrection against the government. Seventeen years before, Sulla had rewarded the soldiers of his victorious army by establishing them in colonies in various parts of Italy, and assigning them allotments of land. Unsuited for an agricultural life, these men had for the most part mismanaged their farms and exhausted their resources. Accordingly they were restless and discontented, and desired nothing so much as a return of the civil wars, with fresh chances of plunder. From among these and other discontented spirits, Catilina began secretly to recruit and organize an army, selecting as his leader one Manlius, who had served with distinction under Sulla as centurion. At the same time he opened secret negotiations with the schools of gladiators in different parts of Italy. Thus prepared, he again stood for the Consulship for the year 62; his intention being to bring about a general rising if he should be once more defeated.
The situation of the government was dangerous in the extreme, for there was no regular army in Italy, and the only general of distinction, Cn. Pompeius, was absent in the East, where after bringing the third Mithridatic war to a close (65) he was occupied in settling the affairs of Syria, and could not be expected to return for some time.
Cicero, however, was kept accurately informed of the progress of the conspiracy. One of its members, Q. Curius, had talked of the plot to his mistress Fulvia. She had not kept the secret; and Cicero, employing her as his agent, had induced Curius by large promises to reveal to him all the details. The consular elections were this year postponed somewhat beyond their usual time. On the day before they should have been held, Cicero induced the Senate to resolve that they should on the next day, instead of holding the election, take into consideration the state of public affairs. He thereupon revealed to them what he knew of the conspiracy, and invited Catilina to clear himself of the charges against him. The latter replied in threatening language; but, notwithstanding his violence, the Senate took no decisive resolution[6]. Shortly afterwards the elections were held; Cicero appearing with a cuirass under his toga, and surrounded by a guard of his friends, to testify to the designs upon his life[7]. Catilina was again defeated, and D. Junius Silanus and L. Licinius Murena elected as Consuls for 62.
Thus once more foiled, Catilina resolved to proceed to active measures. Alarmed at the news that an army was actually collecting in Etruria, and roused by further disclosures from Cicero[8], the Senate, on October 21, passed what was known as the 'Ultimum Decretum;' 'videant consules ne quid detrimenti respublica capiat.' This, the usual formula in cases of emergency, declared the State to be in danger, and called on the Consuls as the executive magistrates to take measures for its safety. Whether it actually conferred any additional powers upon them, is not certain[9]. At the same time they placed the gladiatorial schools under strict surveillance, established patrols in the city, and offered large rewards for information. The praetors, Q. Pompeius Rufus and Q. Metellus Celer, were sent to Capua and Picenum respectively to raise what troops they could. Cicero had already detached his colleague Antonius from the conspiracy, and induced him to support the cause of order, by ceding to him the lucrative province of Macedonia[10].
On October 27 Manlius set up his standard at Faesulae in Etruria. Catilina proposed to go thither himself shortly; he was anxious however to conceal his designs as long as possible, and having been indicted for inciting to riot (de vi) by L. Paullus, he had offered to place himself in free custody[11] under the charge of some citizen of reputation in order to disarm suspicion.
On the night of November 6, he assembled his partisans in the house of M. Porcius Laeca. There he disclosed his plans, and declared it to be essential to success that Cicero should be removed before his own departure. Two of his adherents, C. Cornelius and L. Vargunteius, undertook the duty of visiting Cicero's house in the early morning, under pretence of giving the customary salutation, and there murdering him.
The attempt was actually made, though probably not until the morning of November 8[12]. But Cicero, who was informed of the plot through the agency previously described, refused his visitors admittance. He immediately summoned the Senate to meet, for the sake of safety, in the temple of Jupiter Stator on the Palatine. The equites thronged the hill in large numbers, to secure the safety of the Consul, and to protest against the designs of the conspirators. Catilina did not scruple to attend, whereupon Cicero rose, and delivered the speech known as the First Catilinarian Oration. He revealed to the Senate all the particulars of the plot, including the attempt upon his own life, denounced Catilina as a public enemy, and called upon him to leave the city. His adversary attempted a few words of exculpation, but the feeling roused by the Consul's address was too strong, and finding himself assailed on all sides by reproaches, he left the Senate abruptly, declaring that his enemies were driving him to ruin, but that if he was to fall he would involve others in his overthrow. The same evening he left the city for Etruria, travelling by the Via Aurelia, which was the coast road, in order to create the impression that he was going into exile at Massilia. He left in the city a large number of adherents, the chief of whom was Cornelius Lentulus Sura, with directions to prosecute the plans previously agreed upon. Cicero on the following day assembled the people in the Forum, and in the Second Catilinarian Oration recounted to them what had taken place in the Senate, explaining and justifying his own action.
In a few days the news arrived that Catilina had joined the camp of Manlius at Faesulae. Upon this the Senate declared them both public enemies. At the same time they issued a proclamation promising immunity to those of their adherents who should lay down their arms before a fixed date. Meanwhile the Consul Antonius was directed to take such military measures as might be necessary against the insurgents, Cicero being retained for the protection of the city.