TOPIC: Julius Caesar crossed the Rubicon

In this week in military history, we explore Julius Caesar’s famous literal crossing of the Rubicon.

Rome became a Republic by the end of 6th Century BC. Continued Roman expansion abroad also brought disputes at home often center around debates on the use of force to extend the empire.

The Romans constructed a strict line of demarcation between how they acted beyond the boundaries of Rome and its Italian homeland and termed it Imperium, literally the right to command and one which did not hold sway at home.

At the end of his term as governor, the Roman Senate, who considered Julius to be a threat to a another Roman leader Pompey, ordered him to disband his army and return to Rome. Caesar offered to disband his army if only Pompey would do the same.

The Senate met on January 7th, 49 BC to discuss how best to govern the situation. They issued the decree senatus consultum ultimum, which called on the magistrates to defend Rome. Those elected magistrates were given the right of imperium themselves, or right to command, allowing them to be general of the Roman army in their Italian territories only. Only elected magistrates could have this right, and any unelected official entering Italy at the head of an army would be in direct conflict – an action Caesar was threatening by his crossing the Rubicon. Caesar learned of the decision on January 10th just as his supporters began to fear for their safety and lives.

In defiance of these orders and threats, Caesar gave orders for several groups of soldiers to travel in civilian attire to Ariminum (modern Rimini).

Later in the evening, he traveled with the Legion XIII and 300 cavalrymen to Ariminum, breaking the imperium, making an armed response inescapable. On crossing the Rubicon River into Italy, he declared 'the die is cast' in Latin. Thus, Julius Caesar started a civil war. Caesar’s victory in the Roman Civil War set up his dictatorship and the beginning of the Imperial Era of Rome.

His victory also however led to social and governmental reforms, which included expansion of Roman citizenship and land grants for veterans. The phrase "crossing the Rubicon" is now a part of the lexicon, a metaphor meaning passing the point of no return.

Join us next time for another segment of This Week in Military History with the Pritzker Military Museum & Library!