Marcin crossed the Danube to avoid so formidable a menace, and took up his next station behind the river at Leipheim, watching to see what Marlborough and the Duke of Baden would do. The Elector of Bavaria, in command of the bridge at Lauingen, stood fast, ready to retire behind the stream. The necessity of such a retreat was spared him. The object of his enemies was soon apparent by the direction their advance assumed. For the immediate object of Marlborough and Baden was not an attack upon the inferior forces of the Elector and Marcin, but, for reasons that will presently be seen, the capture of Donauwörth, and their direct march upon Donauwörth took them well north of the Danube. On the 26th, therefore, Marcin thought it prudent to recross the Danube. He and the Elector joined forces on the north side of the Danube, and lay from Lauingen to Dillingen, commanding two bridges behind them for the crossing of the stream, and fairly entrenched upon their front. Meanwhile their enemies, the allies, passed north of them at Gingen. This situation endured for three days.[4] When it was apparent that the allied forces of the English general and the Duke of Baden intended to make themselves masters of Donauwörth (and the Elector of Bavaria could have no doubt of their intentions after the 29th of July, when their march eastward from Gingen was resumed), a Franco-Bavarian force was at once detached by him to defend that town, and it is necessary henceforward to understand why Donauwörth was of such importance to Marlborough's plan. It was his intention to enter Bavaria so as to put a pressure upon the Elector, whose immediate and personal interests were bound up with the villages and towns of his possessions. The Elector could not afford to neglect the misfortunes of its civilian inhabitants, even for the ends of his own general strategy; still less could he sacrifice those subjects of his for the strategic advantage of the King of France and his marshal. This Marlborough knew. To enter Bavaria, to occupy its towns (only one of which, Ingolstadt, was tolerably fortified), and if possible to take its capital, Munich, had been from its inception the whole business and strategic motive of his march to the Danube. But if Marlborough desired to enter Bavaria, Donauwörth was the key to Bavaria from the side upon which he was approaching. This word "key" is so often used in military history, without any explanation of it which may render it significant to the reader, that I will pause a moment to show _why_ Donauwörth might properly be called in metaphor the "key" of Bavaria to one advancing from the north and west.