The famous Roman general who crossed the Rubicon was Julius Caesar in 49 BCE. This act of crossing the Rubicon River with his army marked a pivotal moment in Roman history, signifying the start of a civil war. The phrase "crossing the Rubicon" has since entered popular culture as a metaphor for making irreversible decisions. By defying the Senate's orders and bringing his troops into Italy, Caesar challenged the existing power structure, which ultimately led to his rise as a dictator and the end of the Roman Republic. This event transformed the political landscape of Rome and set the stage for the rise of the Roman Empire.