Final answer:
Caesar was the great Roman general who was governor of Gaul before marching upon the city of Rome.
Step-by-step explanation:
The great Roman general who was governor of Gaul before marching upon the city of Rome was Caesar. Caesar played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire. He fought in Gaul for ten years, capturing and killing many barbarians, reducing tribes and towns to subjection. His military campaign in Gaul was a significant part of his rise to power.