Julius Caesar
In ancient Rome the small river known as the Rubicon marked the boundary between the Roman province of Cisalpine Gaul and the rest of Italy (controlled directly by Rome and its allies) to the south. Julius Caesar had been governor of an area on the north of the river but as his term ended was ordered to return to Rome after having disbanded his troops; it was illegal to bring armed forces into the land on the south side of the river. However, in early 49 BC Julius Caesar led a force over the river and in so doing effectively declared war on the Roman Senate. His action resulted in a three-year civil war that left Caesar ruler of the Roman world.
