The general conspiracy which terrified the Romans under the reign of Marcus Antoninus, comprehended almost all the nations of Germany, and even Sarmatia, from the mouth of the Rhine to that of the Danube. It is impossible for us to determine whether this hasty confederation was formed by necessity, by reason, or by passion; but we may rest assured, that the barbarians were neither allured by the indolence, nor provoked by the ambition, of the Roman monarch. This dangerous invasion required all the firmness and vigilance of Marcus. He fixed generals of ability in the several stations of attack, and assumed in person the conduct of the most important province on the Upper Danube. After a long and doubtful conflict, the spirit of the barbarians was subdued. The Quadi and the Marcomanni, who had taken the lead in the war, were the most severely punished in its catastrophe. They were commanded to retire five miles from their own banks of the Danube, and to deliver up the flower of the youth, who were immediately sent into Britain, a remote island, where they might be secure as hostages, and useful as soldiers. On the frequent rebellions of the Quadi and Marcomanni, the irritated emperor resolved to reduce their country into the form of a province. His designs were disappointed by death. This formidable league, however, the only one that appears in the two first centuries of the Imperial history, was entirely dissipated, without leaving any traces behind in Germany.