An impressive fort, the Castrum Rauracense, was erected on the banks of the River Rhine around AD 300. It replaced the Kastelen compound. Military personnel and the civilian population sought shelter inside the fortification from that point onwards. The fort was destroyed by Germanic tribes in AD 351 or 352. Not long thereafter it was renovated and refurbished. Many Roman troops were withdrawn from the area in AD 401. However, it was still officially a part of the Roman Empire. It was not until the second half of the 5th century that Rome lost its control over the region north of the Alps.