The Imperial Guards were commanded by the Marshals Mortier and Lefebvre and were divided into two corps, the old guard and the young guard 47,000
There was the engineer park, composed of sappers, miners, pontooneers and military mechanicians of all descriptions, the artillery park, and train of wagons with attendants and horses. To these two trains alone belonged 18 thousand horses.
In the active army which marched toward Russia there were 423 thousand well drilled soldiers; namely, 300 thousand infantry, 70 thousand cavalry and 30 thousand artillery with 1 thousand cannon, 6 pontoon trains, ambulances, and also provisions for one month.
As reserve, the ninth corps—Marshal Victor—and the tenth corps—Augereau—were stationed near Magdeburg, ready to complete the army gradually.
The whole army which marched to Russia consisted of 620 thousand men.
The question of subsistence for this immense body occupied Napoleon chiefly. He felt the extraordinary difficulty and great danger, he knew that at the moment of coming in contact with the enemy all the corps would be out of supplies in twenty or twenty-five days if there were no great reserves of bread, biscuit, rice, etc., closely following the army.
His system was that of requisition. To secure the needed supplies the commanders of the corps were ordered to seize in the country all the grain which could be found and at once to convert it into flour, with methodic activity.
Napoleon himself superintended and hastened the work. At twenty different places along the Vistula he had the grinding done unceasingly, distributing the flour thus obtained among the corps and expediting its transport by every possible means. He even invented new measures for this purpose, among which the well-known formation of battalions of cattle, an immense rolling stock destined to follow the columns to serve twofold: for transportation of provisions, and finally as food.
With the beginning of June these supreme preparations had been made or seemed to have been made. In the lands through which the troops were to march before they reached the Niemen, the spring had done its work; there was abundance of forage.
Napoleon had impatiently awaited this time during ten months of secret activity.