On January 10, 49 BCE Gaius Julius Caesar crossed the Rubicon River in northern Italy and thus started a civil war against Pompey and the Senate. In the days of the Roman Republic, the Rubicon was a border river between Pre-Alpine Gaul and Italy, and due to the growing political power of Julius Caesar, the Senate drew a border on the river, which he could not cross due to your legions. It was supposed to be a safeguard against a possible coup d’état.
As we know, however, Caesar crossed this river and Suetonius left us the message of this event. Then, while crossing the Rubicon, Caesar was to say the words Alea iacta est! (traditionally “The dice have been cast”), which was meant to mean making an irreversible decision or step of great importance. The phrase was most likely taken by Caesar from a comedy by the Greek writer Menander Arrephorus1.
The historian describes this event as follows:
Then, overtaking his cohorts at the river Rubicon, which was the boundary of his province, he paused for a while, and realising what a step he was taking, he turned to those about him and said: “Even yet we may draw back; but once cross yon little bridge, and the whole issue is with the sword.”
As he stood in doubt, this sign was given him. On a sudden there appeared hard by a being of wondrous stature and beauty, who sat and played upon a reed; and when not only the shepherds flocked to hear him, but many of the soldiers left their posts, and among them some of the trumpeters, the apparition snatched a trumpet from one of them, rushed to the river, and sounding the war-note with mighty blast, strode to the opposite bank. Then Caesar cried: “Take we the course which the signs of the gods and the false dealing of our foes point out. The die is cast,” said he.
– Suetonius, Caesar, 31-32
Under Roman law in the republic, provincial governors were officials with the power of imperium (the right to command an army) within their provinces. Thus, they could not operate their troops outside their sphere of influence. Roman law only allowed the consuls and praetors to keep imperium in the lands of Italy. If a general did not have special powers to enter Italian lands, he had to disband the army first. A person who did not obey this law and entered Italy at the head of the army automatically lost imperium and command of the army and was sentenced to death. Moreover, soldiers who maintained their obedience to the commander without official authority were also subject to the death penalty.