The die is cast
The Rubicon was the legal boundary river between Italy proper and the provinces, and to cross it with an army was treason. In January 49 BC Caesar lingered long at the river’s edge and said to his officers: not to cross it is my personal ruin; to cross it is the ruin of all mankind. Then, quoting the line from a Greek comedy, "the die is cast," he spurred his horse into the water. "Crossing the Rubicon" thereafter became the standard phrase in Western languages for "an irreversible decision." Worth remembering is his whole stake at that moment: one legion, five thousand men — against Pompey and the entire lawful government.
The Ides of March
A soothsayer had warned him to beware the Ides of March. On the day, meeting the soothsayer on his way to the Senate, Caesar said with a smile, "The Ides of March have come." The man answered, "They have come, but they are not yet gone." The meeting was held in the Theatre of Pompey — at the foot of his enemy’s statue. The assassins crowded around under pretense of a petition, Casca struck the first blow at the neck, and more than sixty rushed in. It is said that when Caesar saw Brutus he stopped resisting, veiled his face with his toga, and fell with twenty-three wounds beneath Pompey’s statue. Shakespeare gave him the Latin line "Et tu, Brute?" — but the histories give it in Greek: "καὶ σύ, τέκνον?" (you too, my child?).