The Roman general who crossed the Rubicon River was Julius Caesar in 49 BCE. This pivotal act was a declaration of civil war against the Roman Senate and his political rivals, as it was illegal for a general to bring an army into Italy. Caesar's crossing of the Rubicon famously represents a point of no return in political and military strategy. His decision ultimately led to the end of the Roman Republic and the rise of imperial authority, culminating in Caesar becoming dictatorial ruler until his assassination in 44 BCE.