A sketch map of Western Russia at the time of Napoleon's invasion in 1812. "The disastrous campaign which opened in June, 1812, was conducted on so vast a scale that a brief sketch can provide only the slightest conception of the magnitude of the operations. The Emperor's forces were divided into three armies. The first, 220,000 strong, which he himself commanded, with Berthier as his Chief-of-staff, was composed of the Guards, three infantry corps under Davout, Oudinot, and Ney, and two cavalry divisions. The second army, 80,000 strong, was commanded by Prince Eugene, and was composed of Eugene's own corps, that of St. Cyr, and one cavalry division. The third army, numbering 80,000 also, was under the command of the Emperor's brother, Jerome, and was made up of three infantry corps under Poniatowski, Vandamme, and Reynier, and one cavalry division. On the extreme left was MacDonald in command of 38,000 men of which the Prussian Auxiliary Corps was a part, and on the extreme right, Schwarzenberg led the Austrian Auxiliary Corps, 30,000 strong. On June 23, 1812, the Emperor's army crossed the Niemen at Kovno and set out for Vilna. One week later, Jerome crossed the river at Grodno, and on the following day Eugene crossed at a point between the other two armies, and followed the Emperor toward Vilna." - Holt, 1920.