Doumerc led his division at the Second Battle of Polotsk on 18 to 20 October. The 3rd Heavy Cavalry Division, including the 4th, 7th, and 14th Cuirassier Regiments, fought at the Battle of Berezina on 26 to 29 December. On the 26th, Oudinot and 11,000 troops, among them the 3rd Heavy, crossed to the west bank of the Berezina River and prepared to defend the two improvised bridges against a Russian attack. The next day, Pavel Chichagov belatedly realized that Napoleon had tricked him out of position and began attacking the French foothold from the south. On the 28th, Chichagov mounted a full-scale attack. During the action Oudinot was badly wounded and replaced in command by Michel Ney. Doumerc led his heavies in a "brilliant charge" that broke the back of Chichagov's effort and inflicted 2,000 casualties on the Russians. This and other heroic actions helped Napoleon's army to escape a deadly trap.