Military preparations had been progressing on both sides during the cessation of hostilities. Napoleon now had a force of 250,000 men distributed as follows: Macdonald lay with 100,000 at Buntzlaw, on the border of Silesia; another corps of 50,000 had their headquarters at Zittau, in Lusatia; St. Cyr, with 20,000 was at Pirna on the great pass from Bohemia; Oudinot at Leipsic, with 60,000; while with the Emperor himself at Dresden remained 25,000 of the Imperial Guard, the flower of France.
Behind the Erzgebirge, or Metallic Mountains, and having their headquarters at Prague, lay the grand army of the allies, consisting of 120,000 Austrians and 80,000 Russians and Prussians; commanded in chief by the Austrian general Schwartzenberg. The French corps at Zittau and Pirna were prepared to encounter these, should the attempt to force their way into Saxony, either on the right or the left of the Elbe. The second army of the allies, consisting of 80,000 Russians and Prussians,—called the army of Silesia,—and commanded by Blucher, lay in advance of Breslau. Lastly, the Crown Prince of Sweden, Bernadotte, who had been influenced by a belief that he was to succeed to the throne of France, was at Berlin, with 30,000 of his own troops, and 60,000 Russians and Prussians. Oudinot and Macdonald were so stationed that he could not approach the upper valley of the Elbe without encountering one of them, and they also had the means of mutual communication and support.
Napoleon had evidently arranged his troops with the view of making isolated assaults, and beating them in detail. He was opposed, however, by generals who were well acquainted with his tactics but none of whom, except Blucher, was above mediocre in generalship. The three allied commanders had prepared counter schemes to frustrate his arrangements, having agreed that whosoever of them should be first assailed or pressed by the French, they should on no account accept battle, but retreat; thus tempting Napoleon in person to follow, leaving Dresden open to the assault of some other great branch of their confederacy, and to enable them at once to seize all his magazines, to break the communications between the remaining divisions of his army, and interpose a hostile force in the rear of them all—between the Elbe and the Rhine.
This plan of campaign is believed to have been drawn up by two of Napoleon's old marshals—Bernadotte and Moreau—both traitors. The latter had just returned from America on the invitation of the Emperor Alexander, whither he had gone after being exiled, and had joined the Allies in their warfare on the French Emperor.
The first movement was made by Blucher, and no sooner did Napoleon become aware that he was threatening the position of Macdonald than he quitted Dresden. He left with his Guard and a powerful force of cavalry on the 15th of August, and proceeded to the support of his marshal. The Prussian commander adhered faithfully to the general plan and retired across the Katsbach, in the face of his enemies. While in pursuit of him Napoleon was informed that Schwartzenberg had rushed down from the Bohemian hills and abandoning Blucher to the care of Macdonald, sent his Guard back to Dresden leaving for the same point himself on the 23d.
Schwartzenberg made his appearance on the heights to the south of the Saxon capital on the 25th, having driven St. Cyr and his 20,000 men before him.
The army of St. Cyr had thrown itself into the city of Dresden and on the 26th were assailed in six columns, each more numerous than its garrison. The French marshal had about begun to despair when the Imperial Guard made its appearance, crossing the bridge from the eastern side of the Elbe, and in their midst was the Emperor himself. His arrival was most timely and the two sallies executed by those troops, hot and tired from their long and tiresome march, caused the allies to be driven back some distance. Night then set in and the two armies remained very near together until the next morning when the battle was renewed amidst a storm of wind and rain.