Cicero's political career was remarkable. In his times, high political offices in Rome, though technically achieved by winning elections, were almost exclusively controlled by a group of wealthy aristocratic families that had held them for many generations. Cicero's family was aristocratic, but did not have great wealth. But Cicero had strong political ambition; at a very young age he chose as his motto the same one Achilles was said to have had: to always be the best and overtop the rest. Lacking the advantages of a proper ancestry, there were essentially only two career options open to him. One was a military career, since military success was thought to result from exceptional personal qualities and could lead to popularity and therefore political opportunity. Cicero, however, was no soldier. He hated war, and served in the military only very briefly as a young man.

Instead, Cicero chose a career in the law. To prepare for this career, he studied jurisprudence, rhetoric, and philosophy. When he felt he was ready, he began taking part in legal cases. A career in the law could lead to political success for several reasons, all of which are still relevant today. First, a lawyer would gain a great deal of experience in making speeches. Second, he (there were no female lawyers in Rome) could also gain exposure and popularity from high-profile cases. Finally, a successful lawyer would build up a network of political connections, which is important now but was even more important in Cicero's time, when political competition was not conducted along party lines or on the basis of ideology, but instead was based on loose, shifting networks of personal friendships and commitments. Cicero proved to be an excellent orator and lawyer, and a shrewd politician. He was elected to each of the principle Roman offices (quaestor, aedile, praetor, and consul) on his first try and at the earliest age at which he was legally allowed to run for them. Having held office made him a member of the Roman Senate. This body had no formal authority -- it could only offer advice -- but its advice was almost always followed. He was, as can be imagined, very proud of his successes.[ref]Though this is not the place for a long discussion of Roman government, it should be noted that the Roman republic was not a democracy. It was really more of an oligarchy than anything else, with a few men wielding almost all economic and political power.[/ref]

During his term as consul (the highest Roman office) in 63 B.C.E. he was responsible for unraveling and exposing the conspiracy of Catiline, which aimed at taking over the Roman state by force, and five of the conspirators were put to death without trial on Cicero's orders. Cicero was proud of this too, claiming that he had singlehandedly saved the commonwealth; many of his contemporaries and many later commentators have suggested that he exaggerated the magnitude of his success. But there can be little doubt that Cicero enjoyed widespread popularity at this time - though his policy regarding the Catilinarian conspirators had also made him enemies, and the executions without trial gave them an opening.

The next few years were very turbulent, and in 60 B.C.E. Julius Caesar, Pompey, and Crassus (often referred to today as the First Triumvirate) combined their resources and took control of Roman politics. Recognizing his popularity and talents, they made several attempts to get Cicero to join them, but Cicero hesitated and eventually refused, preferring to remain loyal to the Senate and the idea of the Republic. This left him open to attacks by his enemies, and in January of 58 B.C.E. one of them, the tribune Clodius (a follower of Caesar's), proposed a law to be applied retroactively stating that anyone who killed a Roman citizen without trial would be stripped of their citizenship and forced into exile. This proposal led to rioting and physical attacks on Cicero, who fled the city. The law passed. Cicero was forbidden to live within 500 miles of Italy, and all his property was confiscated. This exile, during which Cicero could not take part in politics, provided the time for his first period of sustained philosophical study as an adult. After roughly a year and a half of exile, the political conditions changed, his property was restored to him, and he was allowed to return to Rome, which he did to great popular approval, claiming that the Republic was restored with him. This was also treated by many as an absurd exaggeration.

Cicero owed a debt to the triumvirate for ending his exile (and for not killing him), and for the next eight years he repaid that debt as a lawyer. Because he still could not engage in politics, he also had time to continue his studies of philosophy, and between 55 and 51 he wrote On the Orator, On the Republic, and On the Laws. The triumvirate, inherently unstable, collapsed with the death of Crassus and in 49 B.C.E. Caesar crossed the Rubicon River, entering Italy with his army and igniting a civil war between himself and Pompey (Caesar's own account of this war still survives). Cicero was on Pompey's side, though halfheartedly. He felt that at this point the question was not whether Rome would be a republic or an empire but whether Pompey or Caesar would be Emperor, and he believed that it would make little difference, for it would be a disaster in either case. Caesar and his forces won in 48 B.C.E., and Caesar became the first Roman emperor. He gave Cicero a pardon and allowed him to return to Rome in July of 47 B.C.E., but Cicero was forced to stay out of politics. Most of the rest of his life was devoted to studying and writing about philosophy, and he produced the rest of his philosophical writings during this time.

Caesar was murdered by a group of senators on the Ides of March in 44 B.C.E. Cicero was a witness to the murder, though he was not a part of the conspiracy. The murder led to another power struggle in which Mark Antony (of "Antony and Cleopatra" fame), Marcus Lepidus, and Octavian (later called Augustus) were the key players. It also gave Cicero, who still hoped that the Republic could be restored, the opportunity for what is considered his finest hour as a politician. With Caesar dead, the Senate once again mattered, and it was to the Senate that Cicero made the series of speeches known as the Philippics (named after the speeches the Greek orator Demosthenes made to rouse the Athenians to fight Philip of Macedon). These speeches called for the Senate to aid Octavian in overcoming Antony (Cicero believed that Octavian, still a teenager, would prove to be a useful tool who could be discarded by the Senate once his purpose was served).

However, Antony, Lepidus, and Octavian were able to come to terms and agreed to share power. Each of them had enemies that he wanted eliminated, and as part of the power-sharing deal each got to eliminate those enemies. Antony put not only Cicero but also his son, his brother, and his nephew on the list of those to be killed (the Philippics are not very nice to him at all, especially the Second Philippic). Though Octavian owed his success in part to Cicero, he chose not to extend his protection to Cicero and his family. Cicero, his brother, and his nephew tried somewhat belatedly to flee Italy. His brother and nephew turned aside to collect more money for the trip, and were killed. Cicero kept going. Plutarch describes the end of Cicero's life:

"Cicero heard [his pursuers] coming and ordered his servants to set the litter [in which he was being carried] down where they were. He…looked steadfastly at his murderers. He was all covered in dust; his hair was long and disordered, and his face was pinched and wasted with his anxieties - so that most of those who stood by covered their faces while Herennius was killing him. His throat was cut as he stretched his neck out from the litter….By Antony's orders Herennius cut off his head and his hands."

Antony then had Cicero's head and hands nailed to the speaker's podium in the Senate as a warning to others. Cicero's son, also named Marcus, who was in Greece at this time, was not executed. He became consul in 30 B.C.E. under Octavian, who had defeated Antony after the Second Triumvirate collapsed. As consul, the younger Marcus got to announce Antony's suicide to the Senate. It is unfortunate that we have no record of this speech.