In what year did Caesar famously cross the Rubicon with his legion, igniting a civil war?

• A. 52 BCE
• B. 49 BCE
• C. 44 BCE
• D. 30 BCE

Answer: (B)

The key idea is that crossing the Rubicon with his legion was Caesar’s irreversible move to go to war with the Roman Senate and Pompey. The Rubicon marked the boundary of Italy; Roman law forbade a general from bringing an army into Italy. By leading his troops across, Caesar proclaimed that he would not submit to the Senate’s commands, effectively declaring war and launching the civil conflict that followed. This moment is linked to the famous line often attributed to him as he crossed, signaling that the decision was made and the path forward was war.

This event happened in 49 BCE, after Caesar had dominated Gaul and the Senate brokered opposition with Pompey. The other dates refer to different moments: 52 BCE relates to Caesar’s Gallic campaigns culminating at Alesia, 44 BCE is when Caesar was assassinated, and 30 BCE marks the end of the civil wars with Octavian’s rise.