The battle of La Rothiere (1 February 1814) was the only instance during the campaign of 1814 where the two Allied armies launched a combined attack on Napoleon's main army,
The campaign began with Blucher on the Allied right and Schwarzenberg on the Allied left, as they advanced west into France. Napoleon concentrated his forces at Chalons-sur-Marne, and then advanced south-east to try and catch Blucher at St. Dizier on the Marne. Blucher had already escaped from this trap, and was moving south-west across Napoleon's front to Brienne on the Aube. Napoleon won a minor victory over Blucher's rearguard at St. Dizier (27 January 1814), and then turned south-west and advanced on Brienne. On 29 January the French attempted to isolate at least part of Blucher's army, while Blucher prepared to retreat south-east towards Bar-sur-Aube and a union with Schwarzenberg's army. The resulting battle of Brienne (29 January 1814) was a narrow French victory, but Blucher managed to escape from the trap, and retreated towards the village of Trannes, south of Brienne, on the east bank of the Aube.
On 30 January Napoleon slowly advanced south to La Rothiere. On 31 January he was fairly quiet, although he did move his centre of operations from Chalons to Arcis-sur-Aube, reflecting the move from the Marne to the Aube.
In the aftermath of the battle of Brienne Blucher and Schwarzenberg met up at Trannes, a few miles to the south. The Allied commanders then decided to risk an attack on Napoleon's main army. Blucher was given command of the attack, which was to be carried out by two of his own corps and two corps from Schwarzenberg's army, around 53,000 men. Blucher provided Sacken's corps and Olsufiev's corps, both of which had fought at Brienne. Schwarzenberg provided Gyulai's corps and Prince Eugen of Wurttemberg's corps. In addition Wrede's 25,000 Bavarians were to operate further to the east to threaten the French left, while Barclay de Tolly's 33,000 Russians provided the reserve. The battle thus involved around 45,000 French and 80,000 Allied troops. The Allies could have committed more men to the battle, but at this stage Schwarzenberg wasn't sure that he wanted to see Napoleon removed from power, fearing that this would only help Prussia and Russia, and not Austria.
Napoleon didn't suspect that he was about to be attacked south of Brienne. Heavy snow made it difficult to track the Allied armies, but the limited reports that did reach him suggested that they might be heading west to Troyes on the Seine. Early on 1 February Napoleon prepared to move towards Troyes. Mortier was ordered to occupy Lesmont (north-west of Brienne), and Ney began to move north from La Rothiere along the road through Brienne.
About noon Victor reported large scale movement near Trannes and Eclance, south of the French position. Napoloen wasn't sure if this was a bluff or a real attack, and so decided to stand his ground until the situation became clearer. As a result his army was exposed to an attack by a much larger Allied force, with some of his 45,000 men already on the road through Brienne.
The battle was fought to the east of the River Aube. The French line ran from the village of Dienville, on the river, east to La Rothiere on the main road into Brienne, then through Le Petit Mesnil where it began to curve back north, to Chaumesnil on the road east from Brienne, with the French far left at Morvilliers. At the start of the battle Marmont was at Morvilliers, with his right wing stretched out towards La Giberie, Victor at Le Petit Mesnil and Chaumesnil with his right flank at La Rothiere and Gerard on the French right, at Dienville, with some troops on the west bank of the Aube. The French cavalry was posted just behind the line, while Ney and the Young Guard eventually formed a reserve nearer Brienne.
Blucher attacked from the south, coming from Trannes on the Brienne road and Eclance. The corps from his army attacked in the centre, with Sacken heading for La Rothiere and Olsufiev towards Petit-Mesnil. Schwarzenberg's corps attacked on the flanks, with Gyukai attacking along the Aube towards the bridge at Dienville and Wurttemberg on the right, towards La Giberie.
The battle started just after 1pm when Osten-Sacken's cavalry attacked La Rothiere. In this early clash the French noticed that the Russian guns were firing high, and Nansouty sent Guyot's light cavalry to attack, killing many Russian gunners. A major cavalry battle then developed either side of La Rothiere. In this part of the battle some of Osten-Sacken's cavalry captured four batteries of horse artillery of the Imperial Guard, taking 24 guns.
The infantry battle began soon afterwards. Sacken's artillery opened fire on La Rothiere, and his infantry managed to capture the southern end of the village. General Duhesme managed to hold onto the market squadron and the north end of the village despite coming under fire from 62 enemy guns. Both sides received reinforcements at La Rothiere, but the village remained in French hands all day.
On the French right Gerard barricaded the bridge at Dienville, and was able to defend the village all day.
At La Giberie Wurttemberg was able to push Marmont's men out of La Giberie, but the French counter-attacked and retook the village.
The crisis of the battle came at around 4pm, when Wrede's Bavarians attacked Napoleon's left flank. Wrede attacked towards Morvilliers, at the far left of the French line, and Chaumesnil, behind the main French line. The French were pushed out of Morvilliers, and the Bavarians advanced further west and captured the woods of Ajou. Their advance was delayed when some of Wurttemberg's chasseurs, operating on the original Allied right, found Wrede's Bavarian cavalry on their right, assumed they were French, and attacked. Even so the Bavarians were soon threatening Chaumesnil.
The French were also in trouble in the centre, where Barclay de Tolly's Russian reserves were threatening to capture La Rothiere.
Napoleon was now threatened by problems on his left and centre. He sent Ney's leading division, part of the Young Guard, to restore the situation at La Rothiere (led by Marshal Oudinot, who was wounded in both legs during the battle). The Russians did manage to get to the northern edge of the village, but were then repulsed by Drouot's Guard Artillery.
On the left Marmont was given part of the Young Guard, some cavalry and a battery of guns, and managed to delay the enemy advance.
By now it was clear to Napoleon that he faced defeat if he remained in place overnight. At 9pm he issued orders for a retreat to the north, and that night his troops moved north into Brienne, then turned west to join Mortier and the Old Guard at Troyes on the Seine.
Both sides lost 6,000 men at La Rothiere, but the French also lost 50 guns and the defeat greatly reduced the morale of the new recruits. Several thousand troops deserted or dropped out on the road to Troyes.
In the aftermath of the battle Napoleon appeared to be in real trouble. The two Allied armies were now united, and had already inflicted one defeat on him. A well organised advance on Paris by the united Allied armies would have been very hard to resist. At this point the Allies played into Napoleon's hands. They decided to split up for the advance on Paris. Schwarzenberg would advance down the Seine and go via Troyes, while Blucher would move north and advance down the Marne via Chalons and Meaux. The two armies would be linked by Wittgenstein's corps.
This deliberate decision to open up a gap between the two armies was made worse by the two commander's different rates of progress. Blucher soon got ahead of Schwarzenberg, and allowed his army to become dangerously stretched out. This gave Napoleon a chance to move north and get into the middle of Blucher's scattered corps. The battle of Champaubert (10 February 1814) marked the start of the 'Six Day's Campaign', one of Napoleon's most impressive campaigns.