The battle of Vauchamps (14 February 1814) was the last French victory during Napoleon's 'Six Days campaign', and saw the French defeat Blucher's attempt to block their path south towards Schwarzenberg's Army of Bohemia, which was advancing on the Seine front.
The first phase of the 1814 campaign hadn't gone well for the French. Napoleon's attempts to prevent Blucher's Army of Silesia and Schwarzenberg's Army of Bohemia from uniting failed, and even exposed the French to an attack by a large part of the combined Allied army (battle of La Rothiere, 1 February 1814). Napoleon managed to escape from this trap, but the Allies had united their armies, and won a victory over Napoleon on his own soil.
In the aftermath of La Rothiere the French retreated to Troyes, and then to Nogent, which Napoleon believed to be Blucher's next target. Instead the Allies had decided to split, with Schwarzenberg advancing along the Seine to pin Napoleon down, while Blucher moved north to the Marne to threaten Paris.
As a result a gap opened up between the Allied armies, and Blucher also allowed gaps to open up between the main components of his own force. This give Napoleon a chance to defeat Blucher's army in detail, and he took it. He advanced north from Nogent and defeated an isolated Russian corps at Champaubert (10 February 1814), before turning west to defeat Sacken and part of Yorck's corps at Montmirail (11 February 1814). Unfortunately for Napoleon Marshal Macdonald had failed to block the crucial bridge over the Marne at Chateau-Thierry, and the retreating Allies were able to escape across the Marne. The battle of Chateau-Thierry (12 February 1814) was thus just a rearguard action.
In the meantime Schwarzenberg was advancing down the Seine, and the troops Napoleon had left in the south to dely him were being forced to retreat. On 13 February the French got a bridge over the Marne and Mortier and part of the cavalry were able to resume the pursuit of Sacken and Yorck. Napoleon returned to Montmirial to prepare to move south, and Macdonald and Kellermann were sent ahead to try and restore the situation. Marmont, who had been left to watch Blucher after the battle of Champaubert, conducted a skilful fighting retreat from Vertus.
Napoleon had Friant's 1st Old Guard Division, Saint-Germain's cavalry, the Guard Cavalry and Marshal Ney at Montmirail, as well as Marmont's retreating forces. General Grouchy was given overall command of the cavalry.
On 14 February Blucher had around 21,000 infantry and 8,400 cavalry, and Napoleon 15,000 infantry and 7,000 cavalry. Another French infantry division was approaching from the south, and worried Blucher, but was too far away to take part in the battle. At the start of the day the Prussians held the village of Vauchamps, one mile to the east of Montmirail.
The French attacked first. General Ricard was ordered to attack the village, while part of the French cavalry prepared to support him from the north. The French soon forced back the most advanced Prussian troops, and in response the main Allied army began to advance from its position at Fromentieres, east of Vauchamps. Kleist's corps was on the Allied right (north of the road), with Kapsevich on the left (south). These Allied reinforcements join up with the defenders of Vauchamps and forced Ricard to retreat. The French threw their cavalry into the battle, and the defenders of Vauchamps were forced to retreat towards the rest of Kleist's and Kapsevich's men.
The French now began a general advance, with Ricard on the left, Lagrange on the right and the Young Guard and Old Guard just behind. Grouchy's cavalry was still operating to the north of the main battlefield, and threatened to cut off any Allied retreat.
By about 2pm Blucher realised that his position was in great danger and ordered a retreat. Grouchy's cavalry harassed his right flanks, inflicting heavy casualties, and then managed to get onto the road east of the Allies, blocking their escape route to Etoges. All the French needed to make their success complete was to get their horse artillery into place, but the muddy conditions prevented them from achieving this, and after a hard fight Blucher was able to get past Grouchy's road block before the French infantry could hit him in the rear.
By the end of the fighting the Allies had lost around 6,000 men (equally split between the Russians and Prussians), and the French only 600. Most of the Allied losses had occurred during the cavalry attacks on the retreating Allied army. Blucher then retreated further east to Chalons, opening up a big gap between the two Allied armies. At first Napoleon considered attacking Blucher once again, but the news from the Seine remained bad, and he was forced to turn south to deal with Schwarzenberg. Once again Napoleon was able to force his direct opponent to retreat, in this case after winning victories at Mormant (17 February 1814), Valjouen (17 February 1814) and Montereau (18 February 1814).
In the long term Napoleon didn't gain much from his victory. Blucher was retreating towards reinforcements, and he was given command of troops from the Army of the North. He soon collected Winzingerode's 30,000 men and these made up for the loses he had suffered during the Six Days, and by the start of March Blucher was ready to move west once again. Once again Napoleon would be forced to abandon a campaign against Schwarzenberg and rush north to try and stop Blucher once again. This time he would be less successful, and the battles of Craonne and Laon would end with the French retreating.