The re-establishment of peace and order in Gaul was primarily dependent on the cohesion of the empire generally; so long as the Italian emperors stationed their troops in the Narbonensis to set aside the Gallic rival, and the latter in turn made as though he would cross the Alps, effective operations against the Germans were of themselves excluded. It was only after that, about the year 272,[95] the then ruler of Gaul, Tetricus, weary of his ungrateful part, had himself brought about the submission of his troops to Aurelianus, the emperor recognised by the Roman senate, that the thought of warding off the Germans could be again entertained. The raids of the Alamanni, who had for almost ten years ravaged upper Italy as far down as Ravenna, had a stop put to them for long by the same able ruler who had brought Gaul back to the empire, and he emphatically defeated one of their tribes, the Juthungi, on the upper Danube. If his government had lasted he would doubtless have renewed the protection of the frontier also in Gaul; after his speedy and sudden end (275) the Germans once more crossed the Rhine and devastated the country far and wide. [Sidenote: Probus.] His successor Probus (from 276), also an able soldier, not merely drove them out afresh--he is said to have taken from them seventy towns--but also advanced again on the aggressive, crossed the Rhine, and drove the Germans back over the Neckar. He did not, however, renew the lines of the earlier time,[96] but contented himself with erecting and occupying at the more important positions of the Rhine _têtes de pont_ on the other bank,--that is, he reverted nearly to such arrangements as had subsisted here before Vespasian. At the same time the Franks were defeated by his generals in the northern province. Great masses of the vanquished Germans were sent as forced settlers to Gaul, and above all to Britain. In this way the frontier of the Rhine was won back and handed over to the later empire. No doubt, like the rule on the right bank of the Rhine, peace on the left had passed away beyond recall. The Alamanni stood in a threatening attitude opposite to Basel and Strassburg, the Franks opposite to Cologne. By their side other tribes presented themselves. The fact that the Burgundiones, once settled beyond the Elbe, advancing westward as far as the upper Main, threatened Gaul, is first mentioned under the emperor Probus; a few years later the Saxons, in concert with the Franks, began their attacks by sea on the north coast of Gaul as on the Roman Britain. But under the--for the most part--vigorous and capable emperors of the Diocletiano-Constantinian house, and even under their immediate successors, the Romans kept the threatening inundation of peoples within measured bounds. [Sidenote: Romanising of the Germans.]