Important cities were Besançon (Vesontio), Strasbourg (Argentoratum), Wiesbaden (Aquae Mattiacae), and Germania Superior's capital, Mainz (Mogontiacum).

Upper Germania was occupied by Gaulish tribes including the Helvetii, Sequani, Leuci, and Treveri, and, on the north bank of the middle Rhine, the remnant of the Germanic troops that had attempted to take Vesontio under Ariovistus, but who were defeated by Caesar in 58 BC.

During a 5-year period in the initial years of his reign (28–23 BC), as Cassius Dio tells us (53.12), Augustus assumed direct governorship of the major senatorial provinces on grounds that they were in danger of insurrection and he alone commanded the troops required to restore security.

Cassius Dio viewed the Germanic tribes as Celts, an impression given perhaps by Belgica, the name assigned to lower Germania at the time.

Thereafter continual conflict prevailed along it, forcing the Romans to conduct punitive expeditions and fortify Germania Superior.

By 12 BC, major bases existed at Xanten (Castra Vetera) and Mainz (Mogontiacum), from which Drusus operated.

At the conclusion of this violent but brief social storm they were rebuilt more extensively than before, with a road connecting Mainz and Augsburg (Augusta Vindelicorum).

At the end of the war against the Chatti Germania Superior was reestablished as an Imperial Roman province in 85, taking large amounts of territory from Gallia Lugdunensis.

Roman defensive works therefore cut across the base of the bulge, denying the protected corridor and shortening the line.

The key point was the shoulder of the bulge at Mogontiacum (Mainz) where the masse de manoevre or strategic reserves were located.

Where Caesar had described burning the wretched brush hovels of the Suebi who had come to fight for Ariovistus, the Chatti and the Alamanni now lived in comfortable Romanized villages around the limes.