The conquest of Donauwerth opened to the king the further side of the Danube, and now the small river Lech alone separated him from Bavaria. The immediate danger of his dominions aroused all Maximilian's activity; and however little he had hitherto disturbed the enemy's progress to his frontier, he now determined to dispute as resolutely the remainder of their course. On the opposite bank of the Lech, near the small town of Rain, Tilly occupied a strongly fortified camp, which, surrounded by three rivers, bade defiance to all attack. All the bridges over the Lech were destroyed; the whole course of the stream protected by strong garrisons as far as Augsburg; and that town itself, which had long betrayed its impatience to follow the example of Nuremberg and Frankfort, secured by a Bavarian garrison, and the disarming of its inhabitants. The Elector himself, with all the troops he could collect, threw himself into Tilly's camp, as if all his hopes centred on this single point, and here the good fortune of the Swedes was to suffer shipwreck forever. Gustavus Adolphus, after subduing the whole territory of Augsburg, on his own side of the river, and opening to his troops a rich supply of necessaries from that quarter, soon appeared on the bank opposite the Bavarian intrenchments. It was now the month of March, when the river, swollen by frequent rains and the melting of the snow from the mountains of the Tyrol, flowed full and rapid between its steep banks. Its boiling current threatened the rash assailants with certain destruction, while from the opposite side the enemy's cannon showed their murderous mouths. If, in despite of the fury both of fire and water, they should accomplish this almost impossible passage, a fresh and vigorous enemy awaited the exhausted troops in an impregnable camp; and when they needed repose and refreshment they must prepare for battle. With exhausted powers they must ascend the hostile intrenchments, whose strength seemed to bid defiance to every assault. A defeat sustained upon this shore would be attended with inevitable destruction, since the same stream which impeded their advance would also cut off their retreat, if fortune should abandon them.