"Alea Iacta Est"
“Alea iacta est is a Latin phrase attributed by Suetonius to Julius Caesar on January 10, 49 B.C. as he led his army across the Rubicon river in Northern Italy. With this step, he entered Italy at the head of his army in defiance of the Senate and began his long civil war against Pompey and the Optimates. The phrase, either in the original Latin or in translation, is used in many languages to indicate that events have passed a point of no return.
The historian Frances Titchener has given a stylized description of the context of Caesar's pronouncement: "We know from [Caesar's journals] that Caesar is not taking this lightly. He knows that if he marches on Rome with his armies, then he is a public enemy, and that he will either have to win, or die. For a Roman patrician like Julius Caesar there is no life without military service; there is no life without service to the state. He cannot simply 'go native' and stay in Gaul, and he does realize that if he goes back to Rome, he would be killed. At this time the northernmost border of the Roman territory in Italy is the River Rubicon. Once someone crosses the River Rubicon, he's in Roman territory. A general must not cross that boundary with his army – he must do what the Romans call lay down his command, which means surrender his right to order troops, and certainly not be carrying weapons.
Caesar and his armies hesitate quite a while at this river while Caesar decides what to do, and Caesar tells us that he informs his soldiers that it's a little tiny bridge across the river, but once they cross it they'll have to fight their way all the way to Rome, and Caesar is well aware that he's risking not just his own life, but those of his loyal soldiers, and he might not win. Pompey is a formidable enemy. It's also impossible to avoid the fact that Caesar was attacking the state, and as a patrician Roman this would have been very difficult for him, equivalent to beating up your father. He wouldn't have done any of this lightly. Finally he makes a decision, it's time to go, and he uses a gambling metaphor: he says 'Roll the dice', 'Alea jacta est'. Once the dice start rolling they cannot be controlled, even though we don't know what it is as the dice roll and tumble. Julius and his men swiftly cross the river and they march double time toward Rome, where they almost beat the messengers sent to inform the Senate of their arrival."