The allies, having worn down the foe, planned a daring move. Blücher persuaded the allied sovereigns to strike from Bohemia at Leipzig, thus turning the flank of the defensive works that the French had thrown up south of Dresden, and cutting their communications with France. He himself would march north-west, join the northern army, and thereafter meet them at Leipzig. This rendezvous he kept, as later he staunchly kept troth with Wellington at Waterloo; and we may detect here, as in 1815, the strategic genius of Gneisenau as the prime motive force. Leaving a small force to screen his former positions at Bautzen, the veteran, with 65,000 men, stealthily set out on his flank march towards Wittenberg, threw two pontoon bridges over the Elbe at Wartenburg, about ten miles above that fortress, drove away Bertrand's battalions who hindered the crossing, and threw up earthworks to protect the bridges (October 3rd). This done, he began to feel about for Bernadotte, and came into touch with him south of Dessau. By this daring march he placed two armies, amounting to 160,000 men, on the north of Napoleon's lines; and his personal influence checked, even if it did not wholly stop, the diplomatic loiterings of the Swedish Crown Prince.[368] Bernadotte's hesitations were finally overcome by the news that Blücher was marching south towards Leipzig. Finally he gave orders to follow him; but we may judge how easy would have been the task of overthrowing Bernadotte's discordant array if Napoleon could have carried out his project of September 30th. As it was, the disaster of Kulm kept the Emperor tethered for some days within a few leagues of Dresden, while Bülow and Blücher saved the campaign for the allies in the north, thereby exciting a patriotic ferment which drove Jerome Bonaparte from Cassel and kept Davoust to the defensive around Hamburg. There the skilful moves of Walmoden with a force of Russians, British, Swedes, and North Germans kept in check the ablest of the French Marshals, and prevented his junction with the Emperor, for which the latter never ceased to struggle. Meanwhile the Grand Army of the allies, strengthened by the approach from Poland of 50,000 Russians of the Army of Reserve, was creeping through the western passes of the Erz into the plains south of Leipzig. This move was not unexpected by Napoleon. The importance of that city was obvious. Situated in the midst of the fertile Saxon plain, the centre of a great system ofroads, its position and its wealth alike marked it out as the place likely to be seized by a daring foe who should seek to cut Napoleon off from France.