The First Triumvirate is a term historians use for an informal political alliance of three prominent men between 59 and 53 BC, during the late Roman Republic: Gaius Julius Caesar, Gnaeus Pompeius Magnus (Pompey the Great), and Marcus Licinius Crassus.
Julius Caesar was a prominent politician with the populares faction and was eventually renowned for his conquest of Gaul (58-50 BC). Pompey was considered the greatest military commander of his time and commanded armies in the Third Servile War (73–71 BC) in Italy and the Third Mithridatic War (73–63 BC) against the Kingdom of Pontus in West Asia. This gave him great prestige and popularity. Crassus was a property speculator, the largest landlord, and the richest man in Rome. Pompey and Crassus had extensive patronage networks. The three men formed an alliance with which they could gather sufficient popular support to counter the stranglehold the Roman Senate had over Roman politics. The Senate had thwarted some bills these men had sponsored. With this alliance they aimed to overcome the senate's resistance to these bills and to have them passed. The alliance had been kept secret until Pompey and Crassus publicly supported a land law proposed by Caesar in 58 BC. According to Goldsworthy, the alliance was "not at heart a union of those with the same political ideals and ambitions", but one where "all seeking personal advantage." The triumvirate lasted from 59 BC until Crassus' death at the Battle of Carrhae, where he was defeated during his campaign against the Parthians in 53 BC, leaving behind an increasingly fractious relationship between Caesar and Pompey as they now had no buffer.
A civil war ensued after Caesar's crossing of the Rubicon with his army in northern Italy in 49 BC. The conflict eventually led to Caesar's victory over Pompey at the Battle of Pharsalus in 48 BC and the latter's assassination in Ptolemaic Egypt where he fled after the battle. In 44 BC Caesar was assassinated in Rome and the following year his heir Octavian (later known as Augustus) formed the Second Triumvirate with Marcus Antonius and Marcus Aemilius Lepidus.
In the background of the formation of this alliance were the frictions between two political factions of the Late Republic, the populares and optimates. The former drew support from the plebeians (the commoners, the majority of the population). Consequently they espoused policies addressing the problems of the urban poor and promoted reforms that would help them, particularly redistribution of land for the landless poor and farm and debt relief. It also challenged the power the nobiles (the aristocracy) exerted over Roman politics through the senate, which was the body that represented its interests. The Optimates were an anti-reform conservative faction that favoured the nobles, and also wanted to limit the power of the plebeian tribunes (the representatives of the plebeians) and the Plebeian Council (the assembly of the plebeians) and strengthen the power of the senate. Julius Caesar was a leading figure of the populares. The origin of the process that led to Caesar seeking the alliance with Pompey and Crassus traces back to the Second Catilinarian conspiracy, which occurred three years earlier in 63 BC when Marcus Tullius Cicero was one of the two consuls.
In 66 BC Catiline, the leader of the plot, presented his candidacy for the consulship, but he was charged with extortion and his candidacy was disallowed because he announced it too late. In 65 BC he was brought to trial along with other men who had carried out killings during the proscriptions (persecutions) of Lucius Cornelius Sulla when the dictator had declared many of his political opponents enemies of the state (81 BC). He received the support of many prominent men and he was acquitted through bribery. In 63 BC Catiline was a candidate for the consulship again. He presented himself as the champion of debtors. Catiline was defeated again and Marcus Tullius Cicero and Gaius Antonius Hybrida were elected. He plotted a coup d'état together with a group of fellow aristocrats and disaffected veterans as a means of preserving his dignitas. One the conspirators, Gaius Manlius, assembled an army in Etruria and civil unrest was prepared in various parts of Italy. Catiline was to lead the conspiracy in Rome, which would have involved arson and the murder of senators. He was then to join Manlius in a march on Rome. The plot was to start with the murder of Cicero. Cicero discovered this, exposed the conspiracy, and produced evidence for the arrest of five conspirators. He had them executed without trial with the backing of a final decree of the Senate – a decree the senate issued at times of emergency. This was done because it was feared that the arrested men might be freed by other plotters. Julius Caesar opposed this measure. When Catiline heard of this he led his forces in Pistoria (Pistoia) with the intention of escaping to northern Italy. He was engaged in battle and defeated.
The summary executions were an expedient to discourage further violence. However, this measure, an unprecedented assertion of senatorial power over the life and death of Roman citizens, backfired for the optimates. It was seen by some as a violation of the right to a trial and led to charge of repressive governance, and gave the populares ammunition with which to challenge the notion of aristocratic dominance in politics and the prestige of the senate. Cicero's speeches in favour of the supremacy of the senate made matters worse. In 63 BC the plebeian tribunes Quintus Caecilius Metellus Nepos Iunior and Calpurnius Bestia, supported by Caesar, sharply criticized Cicero, who came close to being tried. The senate was also attacked on the ground that it did not have the right to condemn any citizens without a trial before the people. Caesar, who was a praetor, proposed that Catullus, a prominent optimate, be relieved from restoring the temple of Jupiter and that the job be given to Pompey. Metellus Nepos proposed a law to recall Pompey to Italy to restore order. Pompey was away commanding the final phase of the Third Mithridatic War (73–63 BC) in the east. Nepos was strongly opposed by Cato the Younger, who in that year was a plebeian tribune and a staunch optimate. The dispute came close to violence; Nepos had armed some of his men. According to Plutarch, the senate announced the intention to issue a final decree to remove Nepos from his office but Cato opposed it. Nepos went to Asia to inform Pompey about the events, even though, as a plebeian tribune, he had no right to be absent from the city. Tatum maintains that Nepos leaving the city even though plebeian tribunes were not allowed to do so was 'a gesture demonstrating the senate's violation of the tribunate.' Caesar also brought a motion to have Pompey recalled to deal with the emergency. Suetonius wrote that Caesar was suspended by a final decree. At first Caesar refused to stand down, but he retired to his home when he heard that some people were ready to coerce him by force of arms. The next day the people demonstrated in favour of his reinstatement and were becoming riotous, but Caesar "held them in check." The senate thanked him publicly, rescinded the decree and reinstated him. The actions of both men intensified the accusations of illegal actions by Cicero and the senate, were seen as a gesture of friendship towards Pompey, and attracted the sympathy of his supporters. Caesar and Nepos forced the senate to play the role of Pompey's opponent and to resort to threaten (in one case) and use (in the other case) a final decree again – the measure whose repressive nature was at the centre of the dispute - thereby exposing it to further charges of tyranny. Public opinion was sensitive to threats to the people's freedom and Cicero's standing deteriorated.
In 62 BC Pompey returned to Italy after winning the Third Mithridatic War against Pontus and Armenia (in present-day eastern Turkey) and annexing Syria. He wanted the senate to ratify the acts of the settlements he had made with the kings and cities in the region en bloc. He was opposed by the optimates led by Lucius Licinius Lucullus, who carried the day in the senate with the support of Cato the Younger. Pompey had taken over the command of the last phase of that war from Lucullus, who felt that he should have been allowed to continue the war and win it. Moreover, when he took over the command of the war Pompey ignored the settlements Lucullus had already made. Lucullus demanded that Pompey should render account for each act individually and separately instead of asking for the approval of all his acts at once in a single vote as if they were the acts of a master. The character of the acts was not known. Each act should be scrutinised, and the senators should ratify those that suited the senate. Appian thought that the optimates, particularly Lucullus, were motivated by jealousy. Crassus cooperated with Lucullus on this matter. Plutarch wrote that when Lucullus returned to Rome after being relieved from his command the senate hoped that it would find in him an opponent of the tyranny of Pompey and a champion of the aristocracy. However, he withdrew from public affairs. Those who looked on the power of Pompey with suspicion made Crassus and Cato the champions of the senatorial party when Lucullus declined the leadership. Plutarch also wrote that Pompey asked the senate to postpone the consular elections so that he could be in Rome to help Marcus Pupius Piso Frugi Calpurnianus to canvass for his candidacy, but Cato swayed the senate to reject this. Plutarch also noted that according to some sources since Cato was the major stumbling block for his ambitions, he asked for the hand of Cato’s elder niece for himself and the hand of the younger one, whereas according to other sources he asked for the hand of Cato’s daughters. The women were happy with this because of Pompey’s high repute, but Cato thought that this was aimed at bribing him by means of a marriage alliance and refused.