Napoleon underrated the difficulties of his advance or else overrated his brother's military capacity.

The King of Westphalia was delayed a few days at Grodno by bad weather and other difficulties; thus Bagration, who had been ordered by the Czar to retire, was able to escape the meshes closing around him by a speedy retreat to Bobruisk, whence he moved northwards.

Napoleon was enraged at this loss of a priceless opportunity, and addressed vehement reproaches to Jerome for his slowness and "small-mindedness." The youngest of the Bonapartes resented this rebuke which ignored the difficulties besetting a rapid advance.

The prospect of being subjected to that prince of martinets, Davoust, chafed his pride; and, throwing up his command, he forthwith returned to the pleasures of Cassel.
By great good fortune, Bagration's force had escaped from the snares strewn in its path by the strategy of Phull and the counter-moves of Napoleon.

The fickle goddess also favoured the rescue of the chief Russian army from imminent peril at Drissa.