When Marcus Junius Brutus, one of the killers, lifted his bloodstained dagger after the assassination, he called out Cicero's name, beseeching him to "restore the Republic!".
[2] A letter Cicero wrote in February 43 BC to Trebonius, one of the conspirators, began, "How I wish that you had invited me to that most glorious banquet on the Ides of March!
This was a clear violation of the Roman constitution and left Caesar's supporters, known as the Caesarian faction, vulnerable to their appointments being declared illegal by the Senate.
Octavian, Caesar's adopted son and heir, arrived in Italy in April and visited Cicero at his villa before heading to Rome.
Cicero lavished praise on Octavian, calling him a "god-sent child", claiming that the young man desired only honour and would not make the same mistakes as Caesar had.
Cicero convinced the two consuls for 43 BC, Aulus Hirtius and Gaius Vibius Pansa, to lead the Senate's armies (with an allied force commanded by Octavian) against Antony.
The senior magistrate on the scene was Decimus Brutus (the propraetor of cisalpine Gaul), who the Senate attempted to appoint in command, but Octavian refused to work with him because he had been one of Julius Caesar's assassins.
Immediately after legislating their alliance into official existence (for a five-year term with consular imperium), the triumvirate began proscribing their enemies and potential rivals.
[7] Most of the proscribed senators sought to flee to the East, particularly to Macedonia where two more of Caesar's assassins, Marcus Junius Brutus and Gaius Cassius Longinus, were attempting to recruit new armies.
He was eventually caught leaving his villa in Formiae in a litter heading for the coast, from where he hoped to embark on a ship to Macedonia.
His head and hands were publicly displayed in the Roman Forum to discourage any who would oppose the new Triumvirate of Octavian, Mark Antony, and Lepidus.