As governor, Caesar fights the peoples of Gaul for eight years and brings the whole country under Rome. He tells the story himself, in the third person.
All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in our Gauls, the third.
Conquering Gaul let Rome secure the Rhine as a natural border. The wars were a key factor in Caesar's win in the civil war, which ended in the fall of the Republic and the rise of the Empire.
Based on Wikipedia: Gallic Wars
Conquering Gaul allowed Rome to secure the natural border of the Rhine river.
The Gallic Wars were a key factor in Caesar's ability to win the Civil War and make himself dictator, culminating in the end of the Roman Republic and the establishment of the Roman Empire.