The original Gallic province had indeed a marked physical frontier in that elevated region of Auvergne and the Cevennes, together with those ranges which come from the Alps to meet the Gallic mountain system on the middle Rhone. It was, however, bordered on two sides by the lands of the free Gauls. So long as this continued its history was a stormy one. The Gauls of the province were ever restive under the Roman yoke. Every commotion outside the province was echoed within it. The haphazard provincial policy of the last century of the Republic ignored, in so far as possible, discomforts which it had not the energy to remedy. It was not until Cæsar became governor that the work was undertaken by the conquest of the Gauls who remained free. But while solving one ethnic problem, Cæsar found himself face to face with another. Germans had made their way into Gaul, and showed every disposition to go farther. He invented a new solution. He converted the German settlements along the river into a military frontier, allowing the immigrants to retain their lands on condition that they prevented their kinsmen from crossing the Rhine. He sought to create an antipathy of interests where there existed no antipathy of race. The plan was but partially successful, and in the end the Roman legionary had to do the work that the German provincial was intended to do. Cæsar evidently aimed in his Gallic wars at the establishment of a physical frontier in the shape of the Rhine. The same policy has been tried again and again since his day. It has invariably been unsuccessful in modern times, simply because the Rhine is not an ethnic boundary. Cæsar left the problem unsolved, and his successors had to take it up where he left it. Under Augustus the policy of advance was first tried. Its failure was due to various causes,—some of them, perhaps, preventible; but one, and perhaps the major, reason for failure was the impossibility of reaching the far borders of the Germanic races. The problem presented itself on the Elbe in a still more difficult form even than on the Rhine, in that the new-sought frontier was farther from the Roman base. After the disaster to Varus in A.D. 9, the policy of advance was given up. The apparently natural, but really artificial, frontier of the Rhine was definitely decided upon. The maintenance of it, owing to its artificiality, absorbed for well nigh a century a large part of the military resources of the empire. But the denationalization and romanization of the Germans within the border created in course of time an ethnic boundary where none had previously existed, and with its creation the problem was for the time being solved. Here, as elsewhere, Roman Imperial policy created an ethnic boundary where it found none.