Question: Why Did Cicero Have to Die?
The great Roman orator and statesman Cicero served Rome as consul during the Catiline conspiracy and took responsibility for ordering the conspirators executed. Although politically expedient at the time, what he did was illegal, and he suffered for it soon after. Cicero also survived the period of the first triumvirate (Pompey, Crassus, and Caesar). However, after Caesar's assassination, Cicero's position became precarious. Soon Cicero had to die, despite support from Caesar's heir, Octavian (Augustus). The Ancient/Classical History forum discusses why Cicero had to go.
Answer: "The one with the strongest vendetta toward Cicero was Marc Antony, whom Cicero considered to be another Catiline. Cicero's Philippics (based in name after the ones uttered by Demosthenes against King Philip of Macedon) definitely sealed his doom. Marc Antony knew that as a dyed-in-the-wool republican Cicero was never going to extend support to the Triumvirates's measures of dealing with Caesar's assassins and the subsequent divisions of the spoils. Octavian [Augustus] sensed this as well, but his ire toward Cicero was tempered by his youthful simplicity and the fact that Octavian did admire men of intellect and learning. Marc Antony was a brute, and Lepidus [the third member of the triumvirate] a toady. Octavian, of the three, showed momentary moderation, but had unfortunately to cave in to the other two who militarily were more powerful than he." - John Marin
See Senior Travel at About.com's Picture of Cicero's Tomb.