yer was not spared from upheavals in the migration period. With the completion of the Limes in the 1st century AD Speyer was no longer a border town. Flourishing times for Speyer continued after the collapse of the Danube border between 166 and 170 in spite of increasing incursions by Germanic tribes across the Limes. For a while the Romans managed to ward off the attacks of the Alemanni which first appeared in 213.
But as of 260 the Limes could no longer contain the constant onslaught of the Alemanni. The Romans retreated back across the Rhine; Speyer once more became a border town and took in people fleeing from the east. The Alemanni managed to cross the Rhine repeatedly, usually in winter, and in a raid in 275 the town was all but destroyed. Traces of the fires are still visible on excavation sites but it is not known what happened to the population. In 286 Diocletian had the northern provinces reorganized; civil and military administration were separated and settlements rebuilt.
By the 4th century AD the settlement had recovered and a garrison was established. In 352 the Alemanni led by Chnodomar attacked along the whole Rhine front and conquered the territory to the west of the river. The Romans under Constantine II and Julian re-established the Rhine border in a the campaigns of 355. Yet the raids of the Alemanni continued. The settlement was not rebuilt. Instead, Valentinian I had the Rhine frontier fortified and small units, each with their own names, posted in garrisons along the river. In Speyer this happened at least by 369 and it was now called Nemetae. The troops posted in Speyer are listed in a military handbook (notitia dignitatum) as Vindices and the garrison remained at least until 422/423. As a refuge for the inhabitants a stronghold was built on the cathedral hill around 370 with walls 2.5 m strong. Its northern section ran parallel to the northern side of the later cathedral. The southern section corresponded with the outline of
