During his reign, Julius Caesar did everything possible to systematically expand the empire's territory. To achieve this he fought numerous battles with many tribes living not only near southern Roman borders. The expansion also regarded eastern and northern terrains. Among the tribes, which Caesar defeated, was the Celtic tribe of Gauls.
The Gaul inhabited by Celtic tribes had been a terrain, which Rome tried make dependent on the Empire. It was much easier due to the political relations between tribes, because the Celts, despite ethnic and cultural unity, failed to establish a single, united country. Most of the population, who worked as farmers, were dependant on tribes' aristocracy, who fought against each other. As a result, two important tribe centres were created. The first of them was gathered around the Sequani and the second aroung the Haeduans, who were Rome's associates. The situation in Gaul became more complicated, when new tribes appeared - Celtic Helvetii and the German Suevi. The latest helped the Sequani in their fights against the Haeduans and settled around Rhine, in the area of Alsace. Caesar's help was requested by the Haeduans and he used it as an excuse to interfere in Gaul's matter and under the cover of defending Celtic tribes from the Germans' attack conquer Gaul. Caesar, reinforced by Celtic troops, first defeated Helvetii and forced them to withdraw from Gaul. Then he attacked the Suevi and made them leave Gaul and settle somehere far from Rhine. Reinforced by new legions all the time, Caesar decided to conquer the terrain of today Belgium. Then he attacked today Brittany and conquered Aquitaine. Despite the conquest of Gaul hasn't been finished yet, the information which were arriving to Rome from Gaul exaggerated Ceasar's achievements, who has looted much during this campaign.
When Rome has suffered an utter prestige loss on its Eastern border, Caesar steadily improved the Roman reign in Gaul. To prevent another German's attack he crossed Rhein and crushed German tribes, which inhabited that area. Then he set out to Britain, to prevent Celts from helping their fellow-tribesmen on the Continent. Meanwhile, the Roman rule and its results like multiple wars and contributions and obligatory national service caused unhappiness and disorders in Gaul. Rome's enemies became very popular at that time.
Caesar managed to fight the revolt in 54 and 53 BC down, but the information, that Caesar's position is becoming weaker all the time has mobilised Celts to start fights. When Caesar was absent the uprising has spread on the whole Gaul and Vercingetorix, the Arverni chieftan, became its leader. He managed to rise above the idea of small tribes and unite all Celts in a common cause. Caesar returned to Gaul, reinforced by new armies, but was defeated in his first battle and had to flee south, towards the Roman border. It seemed, that this time the Romans would return home with nothing and this defeat would finish Caesar's career. But the Romans were attacked by Vercingetorix's army and won this battle. He managed to crush the chieftan's cavalry with German mercenaries and surrounded him in one of his strongholds. The Gauls tried to free their leader many times, but Caesar was already fortified and fought all of them back and when the people in the fortress started to die of starvation Vercingetorix surrendered in 52 BC. With this victory and taking Vercingetorix captive the uprising was finished and Caesar could start organising the newly conquered country. Now its army and money were at his disposal. And Caesar surely needed them, because in Rome his situation became unfavourable due to Pompei's agreement with the senate.