When the Roman general Julius Caesar reached the Rhine in the summer of 58 BCE, he accepted this river as the frontier between his conquests in Gaul and the region that he left to the Germanic tribes. This suggests that the river was a real border between the Celtic culture of Gaul and the Germanic culture across the Rhine. This is wrong. The tribes on the eastern bank spoke a language that resembled Celtic and, archaeologically speaking, belonged to a culture that was close to the Celtic La Tène-culture. If we call these tribes "Germanic", it is only because Caesar had used this word to describe all inhabitants of the east bank of the Rhine.
One of these tribes was that of the Sugambri, who lived in the area of the rivers Ruhr and Lippe. They are the "parent tribe" of the Cugerni. During the years after 17 BCE, they were among Rome's most aggressive and competent enemies, even able to overcome the two-legion army of Marcus Lollius, the governor of Gallia Belgica, and captured the eagle standard of the Fifth Legion Alaudae (clades Lolliana). The emperor Augustus now understood that the Rhine frontier was still unstable and sent his stepsons Drusus and Tiberius to the north, where they had to pacify the country between Alps, Rhine and Elbe.
In 12, they were ready to attack. The Sugambri understood that they were doomed and decided upon a preemptive strike, but Drusus defeated them twice: on the banks of the Rhine and in their homeland. Next year, Drusus invaded their country for a second time. He proceeded along the Lippe, reached the Cherusci, and would have crossed the Weser if the omens had been better. On his return, he founded a large military base among the Sugambri, which has been discovered by archaeologists near the German town Oberaden. The site can dendrochronologically be dated to the autumn of 11 BCE. Three legions used it as their winter quarters.
Two years later, Drusus died, and was succeeded by his brother Tiberius. In the years 9 and 8, Tiberius attacked the Sugambri and deported 40,000 of them to the west bank of the Rhine. They became known as the Cugerni and lived in farms near Castra Vetera, where Tiberius stationed the the Seventeenth and Eighteenth legions.
The capital of the Cugerni was Cibernodorum, "marketplace of the Cugerni", in the neighborhood of modern Xanten. (Ciberni, Cuberni, and Cugerni are all Latin renderings of the same Germanic name. The Romans found it difficult to pronounce a consonant between /g/ and /b/.) There were other settlements as well. Some of them were occupied before the Sugambri were forced to settle on the Rhine's left bank, which suggests that the ethnic unit of the Cugerni is a mixture of a native population and a Germanic tribe. Religiously, they became Romans, sacrificing to the gods that were also venerated by the legionaries, although the cult of Hludana may have been adopted by the soldiers
All this is not without parallel. In 39 BCE (or a bit later), the Roman general Marcus Vipsanius Agrippa resettled the Ubians, a Germanic tribe from the east bank of the Rhine, on the west bank, where they founded Cologne. At the same time, a part of the tribe of the Chatti migrated to the Lower Rhine and Waal, where it mixed with the natives and accepted their ancient name: Batavians, "people of the fertile wetlands". Their capital was Nijmegen.
All these newly created ethnic units were loyal to Rome. Young and ambitious men served in the auxiliary units of the Roman army. We know of the existence of a First Cugernian Cohort. It may have taken part in Claudius' invasion of Britain in 43, because its presence in this province is attested by a military diploma. Although this text belongs to the year 103, an earlier presence in Britain is certainly possible, because we know that several Batavian cohorts and legion XX Valeria Victrix from Germania Inferior took part in the conquest of Britain.
In fact, the Roman army was generous to the Cugerni. When the seventeenth and eighteenth legions were destroyed in the battle in the Teutoburg Forest (September 9 CE), they were replaced by V Alaudae and XXI Rapax (later: XV Primigenia). For almost eighty years, 10,000 legionaries and numerous auxiliaries spent their pay in the country of the Cugerni. In the Roman world, Germania Inferior was an investment zone, and many Cugerni must have been bussinessmen and artisans. Others were farmers and peasants, and produced food for the soldiers.
Therefore, it comes as a surprise that in 69, the Cugerni sided with the Batavians when they revolted against Rome. It is likely that the people from Cibernodurum had suffered from the same forced recruitments that had caused the Batavians to revolt. The two tribes attacked, captured, and sacked Castra Vetera, the most important symbol of Roman power in Germania Inferior.
The Roman general Petillius Cerialis restored order in the summer of 70. Castra Vetera and Cibernodurum, which had suffered from the fighting, were rebuilt. From this moment on, the Cugerni lost their tribal nature and became a normal Roman municipality.
At the beginning of the reign of Trajan, whose full name was Marcus Ulpius Traianus, the capital of the Cugerni received the status of colonia (between 98 and 107) and was called after the emperor, Colonia Ulpia Traiana. The town was now rebuilt again on a grand scale; about 10,000 people lived within its walls, which had a length of 3.4 km. After Cologne, it was the largest town of Germania Inferior. The name Cugerni was no longer used; instead, people started to call themselved Traianensis.
It seems that the First Cugernian Cohort was renamed as well: two inscriptions refer to a Cohors Ulpia Traiana Cugernorum civium Romanorum ("the Ulpian Traian cohort of Cugernian Roman citizens"). It was stationed at Carrawburgh on Hadrian's wall, but was later transferred to Cramond in Scotland. When the Antonine wall was abandoned, the Ulpian Traian cohort of Cugernian Roman citizens was removed back to the Hadrianic frontier at Newcastle.
One final remark: what happened to those Sugambri who were not transferred to the west bank of the Rhine? They are probably identical to the tribe of the Marsi that is known from several sources. Like other tribes on the Rhine's east bank, they were weakened by the forced migrations, and fell victim to the Germanic tribes.
By the mid-third century, a new ethnic group was living in the former Sugambrian country: the Franks. Unlike the Sugambri, which had belonged to the Celtic La Tène-culture, the Franks were a "real" Germanic tribe. Caesar had once made as distinction between the more or less civilized Gallic and the barbaric Germanic tribes to the west and east of the Rhine; three centuries later, the situation started to resemble its description.