But this period of grandeur was followed by the gradual downfall of the empire, which was already rotten at the core. The degenerate Romans of the later times were unable to stand against the attacks of the more vigorous Germans. The story is too long to tell in detail, but a few points may be briefly noted. In 264 A.D. the Alamanni swept through the country on their way to Gaul, levelling Augusta Rauracorum with the ground, and considerably injuring Aventicum. At the end of the third century the Romans relinquished their rampart between the Rhine and the Danube, and fell back upon the old military frontier of the first century. Helvetia thus underwent a second military occupation. Yet the prestige of Rome was gone. In 305 A.D. the Alamanni again overran Helvetia, and completed the ruin of Aventicum. Weaker and weaker grew the Roman power, and when the Goths pressed into Italy the imperial troops were entirely withdrawn from Helvetia. As for the Helvetians themselves, they were quite unable to offer any resistance, and when the Alamanni once more burst into the land (406 A.D.), they were able to secure entire possession of the eastern portions. The Burgundians, another German tribe, followed suit, and in 443 A.D. fixed themselves in West Helvetia. The inaccessible fastnesses of Graubünden alone remained untouched by the tide of German invasion, which effected such changes in the neighbouring districts. At this period of worldly grandeur and internal decay, occurs another historical event of the greatest importance, the rise of Christianity, containing the vital elements necessary for bringing about the spiritual regeneration of the world. The social and political decomposition throughout the empire, the cruel tyranny of the sovereigns, the decrepitude of the state and its institutions, the growing indifference to the national religion, which showed itself in the facile adoption of, or rather adaptation to, the Eastern forms of worship--the adoption of the deities Isis and Mithra, for example--all these and many other things unnecessary to mention, were unmistakable signs that Roman rule was drawing to its close, and they also prepared the way for the reception of the new doctrine. The belief in one God of mercy and love; of one Saviour, the Redeemer of the world; of a future life,--were startling but good tidings to the poor and oppressed, and made their influence felt also on the rich and cultivated, who saw in Christianity a tolerance, benevolence, human love, loftiness of principle and moral perfection which had not been attained by the creeds of antiquity. The passionate ardour and force of conviction amongst the Christians was such that they faced suffering and death rather than abjure their tenets or desist from preaching them to others.