Belgica was part of the areas conquered by Julius Caesar in his conquest of Gaul in the Gallic Wars (58-50 BC). Gallia (Gaul) was then divided into the Roman provinces of Gallia Narbonensis, Gallia Aquitania, Gallia Lugdunensis and Gallia Belgica. Caesar's conquests along the river Rhine became Germania Superior and Germania Inferior.

Caesar fought against the Belgae in the third of his six campaigns in Gaul. He marched against the Belgae because they had attacked another Gallic group which was a Roman ally. A tough war ensued and the Belgae surrendered after facing heavy losses.

Caesar presented his war with the Gallic peoples as necessary to prevent migrations by the Helveti (Celts from Switzerland) and Sueves (Germanic peoples from the other side of the river Rhine) into areas of eastern Gaul which were close to the Roman possessions in southern Gaul (Gallia Narbonensis) and threatened both this area and Italy. Most historians agree Caesar wanted war to boost his political career and popularity (victors were seen as heroes in Rome) and to amass a large a fortune through war booty to repay his massive debts.

The Gallic Wars started with a clash with the Helveti. They wanted to migrate into eastern Gaul. Caesar refused to give them a safe passage through the area near Geneva. He mobilised two legions from Italy, fortified Geneva, fought the Helveti and defeated them.

Next Caesar fought the Sueves who had defeated the Aedui of eastern Gaul, settled some of their people there and were planning to take over the Sequani (another Gallic people in the area) and bring in more settlers. After his victory against the Helveti, the Gallic peoples summoned Caesar to their general assembly. They asked him to remove the king of the Sueves and the threat of further invasions. Caesar could not do this because the senate had declared the Sueves friends. An attack on the Aedui by allies of the Sueves and news that many Sueves were preparing to cross the river Rhine and that the king of the Sueves was going to attack the largest town of the Sequani gave Caesar a pretext for war.

After conquering the Belgae, Caesar pushed his conquests to the river Rhine However the Eburones, a Gallic group in the northeast, rebelled and were treated harshly. This led to a pan-Gallic revolt led by Vercingetorix, which threatened Caesar and which he suppressed at great cost.

Depends in what time, rome used to be allied to little bit of babarian tribes and still to the end. But, the roman empire or the republic weren't allied secretly to nobody, it like if i was your fake freind without you noticed it at the end. almost all of there allied were slowely conquered by them. a good example will be ancient egypt when rome used to be a republic they were allied until a time when cleopatra was allied with mark antony and then rome conquerd them.

The Celts is a broad term for many different tribes. The people of Gaul were a mix of Celtic (Gallic), Celto-Germanic (the Belgians) and Germanic. There were even Celts living in Northern Italy who were part of Rome.

Positive:

1. For the southern Gauls who traded with and were allied to Rome (Aedui), Caesar was essentially an ally who helped save them from rival tribes (Helvetii) who threatened to steal their lands and take over. He also defeated the invading Germans in his second campaign. This was all at the expense of being subject to Caesar, however.

2. He put an end to human sacrifice. This was still a common practice of the Celts of Caesar's day. People tend to forget how dark some of the Celtic religious beliefs were.

3. Most of the Gauls were granted either citizenship or a preliminary privilege called the Latin Rights. Meaning they had the rights of Roman citizens.

Negative

1. All of these pros came with the expense of incredible loss of life. The Celts are famous for being disorganized. After Caesar defeated the Germans, the Belgians united hoping to be rid of Rome as well. From that point on Caesar decided to conquer all of Gaul. While a million deaths is an exaggeration, hundreds of thousands who fought against him were killed or sold into slavery as Caesar made his way through Gaul.

2. "The loss of Celtic culture" I put this in quotes because this is somewhat overstated and indirect. While it is true Gaul became much more latinized with Caesar, the real death-blow to Celtic culture in Gaul (and Britain) came with advent of Christianity and then the later barbarian invasions of the Franks and others. But the process could be said to have started with Caesar.

It is not a pro or a con, but had Caesar been defeated, modern Europe would be a vastly different place.

While Julius Caesar was governor of the province of Gaul (which then only included southern France, there were rivalries between Gallic peoples beyond this province. In 63 BC, the Sequani and Arverni helped by the Suebi (a Germanic people) defeated and massacred the Aedui who were allies of Rome. They asked Rome for help. The Romans feared that these peoples were going to migrate south, towards Italy. Caesar moved into central Gaul. In response, the Gallic peoples of north-eastern Gaul armed themselves. This led to the Gallic Wars (58-50 BC) in which Caesar conquered Gaul, - which also included Belgium and Holland south of the river Rhine. Caesar also conducted two expeditions in southeastern England .