On the Ides of March (15 March; see Roman calendar) of 44 BC, Caesar was due to appear at a session of the Senate. Mark Antony, having vaguely learned of the plot the night before from a terrified Liberator named Servilius Casca, and fearing the worst, went to head Caesar off. The plotters, however, had anticipated this and, fearing that Antony would come to Caesar’s aid, had arranged for Trebonius to intercept him just as he approached the portico ofTheatre of Pompey, where the session was to be held, and detain him outside. (Plutarch, however, assigns this action to delay Antony toBrutus Albinus). When he heard the commotion from the senate chamber, Antony fled.

According to Plutarch, as Caesar arrived at the Senate, Tillius Cimber presented him with a petition to recall his exiled brother. The other conspirators crowded round to offer support. Both Plutarch and Suetonius say that Caesar waved him away, but Cimber grabbed his shoulders and pulled down Caesar’s tunic. Caesar then cried to Cimber, “Why, this is violence!” (“Ista quidem vis est!”). At the same time, Casca produced his dagger and made a glancing thrust at the dictator’s neck. Caesar turned around quickly and caught Casca by the arm. According to Plutarch, he said in Latin, “Casca, you villain, what are you doing?” Casca, frightened, shouted, “Help, brother!” in Greek (“ἀδελφέ, βοήθει”, “adelphe, boethei”). Within moments, the entire group, including Brutus, was striking out at the dictator. Caesar attempted to get away, but, blinded by blood, he tripped and fell; the men continued stabbing him as he lay defenceless on the lower steps of the portico. According to Eutropius, around 60 or more men participated in the assassination. He was stabbed 23 times. 

According to Suetonius, a physician later established that only one wound, the second one to his chest, had been lethal.

http://en.wikipedia.org/wiki/Julius_Caesar#Assassination

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