"the younger Brutus had been condemned of ingratitude, and the elder of parricide"
The Lictors Bring to Brutus the Bodies of His Sons
Public DomainThe Lictors Bring to Brutus the Bodies of His Sons - Credit: Jacques-Louis David (1748–1825)

Lucius Junius Brutus (the elder) was the founder of the Roman Republic.  He led the revolt that overthrew Rome’s last king, Lucius Tarquinius Superbus, around 509 BC.  The king was Brutus’ uncle, and was responsible for various reprehensible acts, including the execution of Brutus' brother. The last straw was the rape of the noblewoman Lucretia, Brutus’ kinswomen, by the king’s son.  After telling Brutus what had befallen her, Lucretia committed suicide.  Brutus led the people of Rome in banishing the Tarquins from the city, and then led them in an oath never to allow any man again to be king in Rome.

The royal family did not go down without a fight however.  They drew a number of leading Roman citizens into a plot to regain their power, including Brutus' wife and his two sons.  When the conspiracy was discovered, Brutus, together with his fellow consuls, determined that the conspirators must be put to death, including the members of Brutus’ family.  Brutus’ act of parricide was thus to preside over the execution of his sons. He was subsequently killed in battle – he and his cousin, a son of the vanquished king, speared each other to death.

 

Brutus the younger
Public DomainBrutus the younger - Credit: Michelangelo

Marcus Junius Brutus (the younger) (85 BC – 42 BC) was a descendent of this republican Brutus.  He was a Senator and one of Julius Caesar’s inner circle.  When Caesar had the Roman Senate declare him dictator for life, there were many among the Senators who feared Caesar sought to become king of Rome.  They persuaded Brutus to join a conspiracy to kill Caesar.  It is said that, on the day of the killing, Caesar blocked the initial knife thrusts but, upon seeing Brutus among the conspirators, resigned himself to die. 

In Shakespeare’s Julius Caesar, Marc Anthony says:

For Brutus, as you know, was Caesar's angel

Judge, O you gods, how dearly Caesar lov'd him!

This was the most unkindest cut of all

For when the noble Caesar saw him stab

Ingratitude, more strong than traitors' arms,

Quite vanquish'd him: then burst his mighty heart. . .

Anthony suggests that Caesar died not so much from his wounds, as from the realization of Brutus' treachery.