Montmirail had been a more decisive victory than Champaubert.

Twenty thousand men had been eliminated from calculations for the time being.

Sending couriers to Macdonald to move down the banks of the Marne with all possible speed, to get in the rear of Yorck, with whom he purposed to deal on the morrow, Napoleon, in high spirits, made preparations for the next day's battle.
The next morning, the thirteenth, leaving a heavy force to check any possible attack by Sacken, who had, with incredible energy and labor, partially at least reorganized his shattered troops, but who was too weak to do anything more than lead them away from any possible touch with Napoleon's troops, the Emperor advanced toward the little village of Chateau-Thierry.

Yorck, by this time, had learned the full details of the disaster to Sacken.

Indeed, several of Sacken's brigades had joined him, considerably augmenting his force.