On January 10, 49 B.C., on the banks of the Rubicon River in southern Gaul (near the modern-day city of Ravenna), Julius Caesar and the soldiers of the 13th Legion waited and weighed their options.
The Rubicon is, in reality, little more than a stream. Its significance to Rome lay in its location, marking the official border between Italy and Cisalpine Gaul, the region south of the Alps governed by Julius Caesar. Despite its appearance, crossing this humble river would have serious consequences. According to the law of the Roman Republic, any provincial governor leading troops across the border back into Italy would be declared a public enemy. It was, quite simply, an act of war.
Huddled against the biting cold, many of the soldiers of the 13th Legion of the army of the Roman Republic had served under Caesar for much of the previous decade. They had witnessed the honing of his skills as a military and political strategist, subjugating Gaul (corresponding to much of modern-day France and northern Italy), extending the bounds of the Roman Republic as far as the Rhine, and all the time shoring up his influence back in Rome. Alarmed by his growing power, the Senate ordered Caesar to set aside his command.