Marcus Junius Brutus (85 BCE to 42 BCE) was a Roman senator most famous for his role in the assassination of Julius Caesar on the Ides of March (15 March) 44 BCE. Said to have been descended from the semi-legendary founder of the Roman Republic, Brutus came to oppose the autocratic behavior shown by Caesar after the latter became dictator. After killing Caesar, Brutus fled east, where he and fellow conspirator Gaius Cassius Longinus put together an army. Brutus was ultimately defeated by Caesar's successors at the Battle of Philippi in 42 BCE and committed suicide shortly thereafter. He is alternately remembered as a noble man who acted in opposition to tyranny or as one of the most notorious traitors in history.

Brutus was born in late 85 BCE to the gens Junia, one of the most storied families in Rome. According to legend, it was their ancestor, Lucius Junius Brutus, who had driven out the last of the kings and established the Roman Republic, serving as one of its first two elected consuls. The Roman historian Livy writes that this Junius Brutus had sworn a holy oath to chase the king and his wicked family from the city and that he would never again let "them or any other man be King in Rome" (1.58). And for centuries, the oath of Brutus stood firm. To be sure, the Republic had had its crises and bloodbaths, demagogues and dictators. But there had been no more kings. The Junia family was proud of their tradition as defenders of Roman liberty. As an adult, Marcus Junius Brutus displayed a family tree in the tablinum of his house.

The Rome of his birth was a turbulent place. His father, also named Marcus Junius Brutus, rebelled against the Roman Senate in 77 BCE. He was besieged by forces under Pompey the Great and, after it became clear that further resistance was futile, surrendered on the understanding that he would be given amnesty. But this was a lie – the elder Brutus was taken and executed, either on Pompey's orders or else underneath his nose. From then on, Brutus's family bore a deep-seated hatred for Pompey. His mother, Servilia, was among the most influential women in Rome. She was a shrewd political operator who arranged advantageous marriages for all three of her daughters. It was an open secret that she was the lover of Julius Caesar, often acting as his confidante and agent in his political negotiations. Indeed, it was widely rumored that Brutus was actually Caesar's lovechild. But since Caesar was only 15 when Brutus was born, modern scholars deem this unlikely.

Growing up, Brutus was an intelligent, handsome boy with a deep interest in philosophy, particularly the Platonists. He had a mop of thick curly hair, piercing deep-set eyes, a straight nose, and a muscular neck. He was, according to historian Barry Strauss, "proud, talented, sober, high-minded, and probably a little vain" (15). Due to his father's sullied reputation, he was unable to start a political career until relatively late in life. For this, he blamed Pompey, a hatred that nearly turned violent. In 59 BCE, Brutus was implicated in the Vettius affair, a plot to murder Pompey. But Brutus was saved from facing any consequences when his name was stricken from the list of conspirators. Since Caesar was serving as consul that year, it is plausible that he had rescued Brutus as a favor to Servilia.

Around 59 BCE, Brutus was adopted by a relative, Quintus Servilius Caepio. Though he continued to go by his birthname rather than his new adoptive name – Quintus Servilius Caepio Brutus – the adoption served to wipe away the stains of his father's treason and allow him to begin his political career. His first job was in 58 BCE when he went to Cyprus to serve as an assistant to his maternal uncle, Cato the Younger, the governor of the province. According to the historian Plutarch, Brutus was quite capable in this position. He also used the opportunity to learn from his uncle Cato, a man he respected and who was often viewed as the epitome of Roman republican ideals.

In 54 BCE, Brutus married Claudia, daughter of the sitting consul Appius Claudius Pulcher. Marriage into the powerful Claudian family likely helped boost his career; the next year, he was elected quaestor and was admitted into the Roman Senate. In 53 BCE, he went to Cilicia to serve under his father-in-law as lieutenant governor. Like many other Roman governors at the time, he used this office to enrich himself by extorting money from the local populace. In one particularly egregious case, he gave a loan to the town of Salamis on Cyprus at the exorbitant annual interest rate of 48%. When the town's leading men failed to pay this back, he sent armed enforcers to lock them in their council house until they could come up with the money. By the time all was said and done, five of the councilmen had died of starvation.

When Brutus returned to Rome in 52 BCE, he found the city in a state of chaos. His uncle-in-law, the rabble-rousing gang leader Publius Clodius Pulcher, had just been murdered, and Pompey had been elected sole consul to restore law and order. This was an unprecedented step that Brutus feared was a precursor to dictatorship. He wrote a pamphlet entitled De Dictatura Pompei ("On the Dictatorship of Pompey") in which he virulently opposed concentrating so much power in one man's hands. "It is better to rule no one than to be another man's slave," he wrote in one of the few surviving fragments, "for one can live honorably without power, but to live as a slave is impossible" (quoted in Tempest, 50).

Around 51 BCE, Brutus won election as a pontifex, an important priesthood overseeing religion and law. It is likely that he secured this job thanks to the support of Caesar, who was away prosecuting his controversial war in Gaul. By now, Pompey and Caesar were the two most powerful men in Rome, and it was clear that relations between them were souring. The Optimates – a conservative faction of Roman senators – wanted Caesar to give up his legions and return to Rome to answer for crimes he had allegedly committed both before and during his Gallic Wars. Failing this, they were prepared to ask Pompey to lead an army against him and bring him to justice. As tensions continued to escalate, Brutus remained silent, refusing to publicly pick a side.

But then, when Caesar crossed the Rubicon with his legions in January 49 BCE, neutrality was no longer an option. In the subsequent civil war, Brutus sided with Pompey and the Optimates – despite his hatred for Pompey, he acted either out of his loyalty to the Republic, which Caesar was invading, or because the men he admired most, like his uncle Cato and the orator Marcus Tullius Cicero, had already thrown their lots in with the Pompeians. It is not known whether he was present at the Battle of Pharsalus in 48 BCE, when Pompey was decisively defeated by Caesar (Pompey was assassinated in Egypt shortly thereafter). However, according to Plutarch, before the battle, Caesar had ordered his men to take Brutus prisoner if he surrendered, but not to harm him if he kept fighting.

After Pharsalus, Brutus wrote to Caesar asking for clemency. Caesar was only too happy to oblige and granted him a full pardon. Some scholars have speculated that Caesar pardoned Brutus out of love for Servilia, while others maintain that he saw the propagandic value of having someone as respected as Brutus defect to his side. In any event, Caesar rewarded Brutus with the prestigious post of governor of Cisalpine Gaul in 46 BCE. This time, Brutus did not extort the local populace; many of these provincials were loyal to Caesar, who would not have allowed them to be taken advantage of. Because of this restraint, Brutus proved to be a popular governor, and at the end of his one-year term, a statue of him was raised in Mediolanum (Milan). In late 45 BCE, Caesar appointed Brutus urban praetor and promised him future offices down the line, including that of consul.

Brutus's career was undoubtedly doing well under Caesar, and he likely felt affection for the older statesman. However, he could not help but feel disturbed at the way things were progressing. Caesar had first been made dictator shortly after the civil war began, but, in 44 BCE, he was appointed dictator for life (dictator perpetuo). By then, he had begun to act increasingly like a monarch. He made significant decisions without consulting the Senate, such as appointing his own officials, granting land to his veteran soldiers, and changing the calendar. He began to dress in high red boots and attended Senate meetings sitting in a golden chair, both reminiscent of Roman kingship. He appeared to insult the Senate by not rising before a senatorial delegation, dismissed two properly elected tribunes, and, at the Lupercalia festival, he was repeatedly offered a crown by his lieutenant, Mark Antony.

Rumors began to swell that Caesar meant to officially make himself king before departing on a military expedition to Parthia in late March 44 BCE. Brutus felt the heavy weight of his family legacy on his shoulders. Graffiti sprang up on the tribune where he sat as urban praetor and on statues of his legendary ancestor, calling him to action with phrases like "wake up, Brutus!" and "you aren't really Brutus" (quoted in Strauss, 80). His friend Cicero wrote him letters asking him to reconsider his allegiance to Caesar, as did his wife, Porcia (he had divorced Claudia in 45 BCE). The daughter of Cato the Younger – and therefore Brutus's cousin – she shared her late father's republican ideals and, according to some ancient sources, was instrumental in convincing Brutus to act. The final straw came on the night of 22 February 44 BCE, when Brutus was visited by his brother-in-law, Gaius Cassius Longinus. Cassius persuaded Brutus that something had to be done to stop Caesar and that no conspiracy would succeed without him.

Brutus not only joined the conspiracy but was soon among its leaders. Alongside Cassius and his distant cousin Decimus Brutus Albinus, he recruited other discontented senators who had reason to oppose the dictator. Ultimately, there were probably around 60 conspirators, of whom only around 20 would go through with the murder itself. Though he agreed that Caesar had to die, Brutus was adamant that they were acting only to remove a single tyrant and urged that they refrain from doing anything that smacked of a coup or regime change. To that end, he dissuaded Cassius from also having Mark Antony killed, and successfully argued against seizing control of any military forces. After mulling over a few different plans, Brutus and the other conspirators decided to attack Caesar at the next Senate meeting, which would be held at the Senate House in the Portico of Pompey on the Ides of March.

Brutus and Cassius arrived early at the portico on the day Caesar was to die. As urban praetor, it was Brutus's job to hear out supplicants who had matters of justice to discuss, and he therefore spent these nerve-wracking hours in calm discussion with men who had business with him. Plutarch remarks that "anyone who knew what was about to happen would have been amazed at the unshakable calm and presence of mind displayed as the critical moment drew near" (quoted in Tempest, 1). Caesar arrived late to the meeting – he had initially decided not to come but had been lured there by Decimus Brutus, his old war buddy. As Caesar entered the building, alone and without a bodyguard, the conspirators closed in and drew their daggers.

"Why, this is violence!" the dictator cried out, shortly before he was stabbed once, then twice. Soon, he was swarmed by a frenzied crowd of senators. As they blindly cut and slashed – Caesar would ultimately be stabbed 23 times – some of the assassins accidentally stabbed one another, with Brutus sustaining a wound to the hand in the confusion. Initially, Caesar defended himself, pushing his assailants away – that is, according to Plutarch, until he noticed Brutus standing there, dagger in hand. At that point, he seems to have given up, burying his head in his robes and yielding to the assassins' blows. William Shakespeare famously has him cry, "Et tu, brute?" but this was just an invention of the bard. Some ancient sources claim that he called out, "And you, my child?" upon seeing Brutus, which may have been a last-minute acknowledgement that Brutus was his son (unlikely) or a curse. Other sources claim he just stayed silent. In any case, he was soon dead, his dark blood pooling on the august floor of the Senate House.

The assassins – or 'Liberators' as they called themselves – marched from the Senate House to the Capitoline Hill, their hands and togas literally stained with Caesar's blood. Defended by gladiators hired by Decimus Brutus, they stayed holed up on the Capitoline for two tense days, making speeches decrying Caesar's tyranny and justifying their actions for the good of the republic. On 17 March, a compromise was reached in the Senate to avoid the effusion of more blood: the Liberators would be given amnesty, and, in exchange, Caesar's reforms and political appointments would stand. Brutus and Cassius descended the hill, but a few days later, a riot at Caesar's funeral – perhaps spurred on by Antony – caused them to fear for their lives. In mid-April, they left Rome and fled to Antium (Anzio).

Brutus and Cassius waited there until early August, at which point they headed East, since Caesar's successors were consolidating their strength and civil war seemed imminent. Brutus bid a tearful goodbye to Porcia in southern Italy, where they parted in front of a painting of Hector and Andromache, the ill-fated heroic couple from the Iliad. Then, Brutus went to Greece, where he enjoyed much sympathy from the rich young sons of the Roman nobility who were studying in Athens. Partly through the support of Roman students in Athens, but mostly through pillaging Greek cities, he gathered enough funds to raise an army and, in January 43 BCE, marched north into Macedonia. There, he captured Mark Antony's brother Gaius (whom he later executed) and spent the next few months building his strength, watching events play out in Italy.

By then, things did not look too good for the Liberators. After a brief civil war to claim the spot of Caesar's heir, the Caesarians had reconciled and formed a power-sharing alliance known as the Second Triumvirate; these new triumvirs included Mark Antony, Marcus Lepidus, and Octavian, Caesar's 19-year-old grandnephew whom the dictator had posthumously adopted in his will. The triumvirs rescinded the amnesty that had been granted to the Liberators, and Brutus, Cassius, and the other conspirators were all convicted of murder in absentia. Brutus, pushing away the grief that came with the news of Porcia's unexpected death in Italy, knew he had to act fast. In January 42 BCE, he joined forces with Cassius, who had been busy recruiting 12 legions of his own in Syria. With their combined army, they decided to wait for these triumvirs to come to them and settle the fate of the republic once and for all.

The triumvirs did come and, in early October 42 BCE, the opposing armies were arrayed outside Philippi in eastern Macedonia. The army of the triumvirate, under Octavian and Antony, had around 95,000 infantry and 13,000 cavalry, while Brutus and Cassius had about 85,000 infantry and 20,000 cavalry. Initially, the odds seemed to be in the favor of the Liberators – they had access to fresh supplies and controlled the high ground. But Brutus did not feel that fortune was on his side. Several months earlier, he had seen a vision of a spirit that told him, "You will see me at Philippi" (quoted in Strauss, 221). Still, he boldly faced his fate, writing to a friend that either they would free the Roman people on the fields of Philippi, or die and be themselves freed from slavery.

The first battle came on 3 October, when Antony flanked Cassius's army and overran his camp. That same day, Brutus's soldiers succeeded in overrunning Octavian's camp, but Cassius, fearing that all had been lost, committed suicide before learning of Brutus's victory. After the battle, each side returned to its initial position, with Brutus's men taking over Cassius's camp. This stalemate continued until 23 October, when Brutus attacked and was defeated. He managed to escape the battlefield and fled into the hills with four legions. As day turned to night and the stars flickered in an ink-black sky, Brutus passed the time quoting Greek literature, telling his friends that he blamed fortune for his defeat and that he would die content. That night, he killed himself by falling on his sword. According to Plutarch, his last words were, "By all means must we fly, but with our hands, not with our feet" (quoted in Tempest, 208). In the millennia that followed, he would be remembered both as one of history's greatest defenders of liberty and as one of its most notorious traitors.