Lejeune, vol. ii., chap. vi. As it chanced, Kutusoff had resolved on retreat, if Napoleon attacked him. This is perhaps the only time when Napoleon erred through excess of prudence. Fezensac noted at Moscow that he would not see or hear the truth.
It has been constantly stated by Napoleon, and by most French historians of this campaign, that his losses were mainly due to an exceptionally severe and early winter. The statement will not bear examination. Sharp cold usually sets in before November 6th in Russia at latitude 55°; the severe weather which he then suffered was succeeded by alternate thaws and slighter frosts until the beginning of December, when intense cold is always expected. Moreover, the bulk of the losses occurred before the first snowstorm. The Grand Army which marched on Smolensk and Moscow may be estimated at 400,000 (including reinforcements). At Viasma, before severe cold set in, it had dwindled to 55,000. We may note here the curious fact, substantiated by Alison, that the French troops stood the cold better than the Poles and North Germans. See too N. Senior's "Conversations," vol. i., p. 239.
Bausset, "Cour de Napoléon"; Wilson, pp. 271-277.