Before crossing the Danube the Visigoths had been required by the Romans to give up their arms, and also a number of their children to be held as hostages. In return it was understood that the Romans would equip them afresh with arms sufficient for their defense and with food supplies to maintain them until they should become settled in their new homes. So far as our information goes, it appears that the Goths fulfilled their part of the contract, or at least were willing to do so. But the Roman officers in Thrace saw an opportunity to enrich themselves by selling food to the famished barbarians at extortionate prices, and a few months of such practices sufficed to arouse all the rage and resentment of which the untamed Teuton was capable. In the summer of 378 the Goths broke out in open revolt and began to avenge themselves by laying waste the Roman lands along the lower Danube frontier. The Eastern emperor, Valens, hastened to the scene of insurrection, but only to lose the great battle of Adrianople, August 9, 378, and to meet his own death. "The battle of Adrianople," says Professor Emerton, "was one of the decisive battles of the world. It taught the Germans that they could beat the legions in open fight and that henceforth it was for them to name the price of peace. It broke once for all the Rhine-Danube frontier." Many times thereafter German armies, and whole tribes, were to play the role of allies of Rome; but neither German nor Roman could be blinded to the fact that the decadent empire of the south lay at the mercy of the stalwart sons of the northern wilderness. Source--Ammianus Marcellinus, _Rerum Gestarum Libri qui Supersunt_, Bk. XXXI., Chaps. 12-14. Translated by Charles D. Yonge [see p. 34], pp. 608-615 _passim_. Text in edition of Victor Gardthausen (Leipzig, 1875), Vol. II., pp. 261-269. [Sidenote: The Goths approach the Roman army]