Only a couple of examples in order to illustrate our ideas.
When Buonaparte crossed the Niemen on 24th June, 1812, the enormous centre of his army with which he subsequently marched against Moscow numbered 301,000 men. At Smolensk, on the 15th August, he detached 13,500, leaving, it is to be supposed, 287,500. The actual state of his army however at that date was only 182,000; he had therefore lost 105,000.(*) Bearing in mind that up to that time only two engagements to speak of had taken place, one between Davoust and Bragathion, the other between Murat and Tolstoy-Osterman, we may put down the losses of the French army in action at 10,000 men at most, and therefore the losses in sick and stragglers within fifty-two days on a march of about seventy miles direct to his front, amounted to 95,000, that is a third part of the whole army.
Three weeks later, at the time of the battle of Borodino, the loss amounted to 144,000 (including the casualties in the battle), and eight days after that again, at Moscow, the number was 198,000. The losses of this army in general were at the commencement of the campaign at the rate of 1/150daily, subsequently they rose to 1/120, and in the last period they increased to 1/19 of the original strength.
The movement of Napoleon from the passage of the Niemen up to Moscow certainly may be called a persistent one; still, we must not forget that it lasted eighty-two days, in which time he only accomplished 120 miles, and that the French army upon two occasions made regular halts, once at Wilna for about fourteen days, and the other time at Witebsk for about eleven days, during which periods many stragglers had time to rejoin. This fourteen weeks’ advance was not made at the worst season of the year, nor over the worst of roads, for it was summer, and the roads along which they marched were mostly sand. It was the immense mass of troops collected on one road, the want of sufficient subsistence, and an enemy who was on the retreat, but by no means in flight, which were the adverse conditions.