Celtic warfare
The "Gallic Wars" were a series of military campaigns waged by the Roman proconsul Julius Caesar against Gallic tribes, lasting from 58 BC to 51 BC. The Romans would also raid Britannia and Germania, but these expeditions never developed into full-scale invasions. The Gallic Wars culminated in the decisive Battle of Alesia in 52 BC, in which a complete Roman victory resulted in the expansion of the Roman Republic over the whole of Gaul. The wars paved the way for Caesar to become the sole ruler of the Roman Republic.
Colonia Claudia Ara Agrippinensium
In AD 260 Postumus made Cologne the capital of the Gallic Empire, which included the German and Gallic provinces, Britannia and the provinces of Hispania. The Gallic Empire lasted only fourteen years. By the 3rd century, only 20,000 people lived in and around the town as the city was badly affected by the crisis of the 3rd century. In AD 310, Emperor Constantine I had a bridge over the Rhine constructed; this was guarded by the "castellum" Divitia (nowadays "Deutz"). In AD 321 Jews are documented in Cologne; when exactly the first Jews arrived in the Rhineland area cannot be established any more, but the Cologne community claims to be the oldest north of the Alps.