He threw Mortier forward on the Chateau-Thierry road to check Yorck.

He put Friant, the veteran and splendid fighter, in echelon along the La Ferte road; withdrew Nansouty's cavalry to cover his own right, and put Ney and Ricard in his main battle line between Friant on the road and the river on the left.

The guard, with Maurice's cavalry d'elite, he posted on the edge of the woodland, north of Montmirail, ready to throw to the northwestward to Marmont, or to the west to the support of Ney and Friant, as events might determine.

These dispositions were barely completed before the battle was joined by the Russian advance.
Sacken, who really outnumbered the forces opposed to him by at least two thousand men, since Mortier's corps, guarding the northwest road, was perforce inactive, and since six thousand men had been left at Champaubert under Marmont to retain Bluecher, attacked with the utmost stubbornness and gallantry.

He could make no impression on Friant, echeloned on the main road, and before the resolute resistance his advancing divisions slowly obliqued to the right toward another walled farmhouse, called Epine-aux-Bois, in a stretch of lowland watered by a brook.
Napoleon, seeing the whole course of the battle clearly, laid a trap for him.