The battle of Rheims (13 March 1814) was Napoleon's last significant success during the 1814 campaign, and saw his troops recapture Rheims in a night attack, briefly causing a panic amongst the Allied commanders.
Earlier in the campaign Napoleon had won a series of victories that kept the Allies off balance, defeating Blucher in the Six Days campaign around the Marne and Schwarzenberg at Mormant, Valjouen and Montereau (18 February 1814) on the Seine. His attempt to inflict more damage on Schwarzenberg's army around the Aube then failed because the Austrian was always willing to retreat if required, and so Napoleon turned north once again to deal with Blucher. Although he was able to force Blucher to retreat north of the Aisne, this part of the campaign ended with a defeat at Laon (9-10 March 1814), when Marmont's isolated wing of the French army suffered a heavy defeat. Napoleon was forced to retreat back to the Aisne.
The gap between the two main Allied armies was filled by a Russian force commanded by General St. Priest, a French emigre. He had originally been posted at St. Dizier, but on 12 March had moved north-west and taken Rheims. This placed him dangerously close to Napoleon on the Aisne, and the Emperor decided to take advantage of this mistake.
Napoleon ordered Marmont, with I Cavalry Corps, to lead the advance on Rheims, followed by the Guard cavalry, Friant's division and Boyer's brigade from the Guard, commanded by Ney.
After the capture of Rhiems St. Priest posted his Russian troops in the city and his Prussian troops in villages to the north and south of the road leading west towards Soissons. As the French advanced they ran into these Prussian troops, and won a series of fairly easy victories. The battalion at Rosnay, south of the road, retreated east to Gueux and was then forced to surrender a little further east, at Ormes. The battalions at Muizons, on the main road, and Thillois, on the same road but closer to Rheims were also surprised and were scattered.
St. Priest still didn't believe that he was facing a serious attack, but he did deploy the remaining part of his force west of Rheims, with his right on the Vesle river at Tinqueux and his left towards the village of Bezannes, where it was guarded by a stream called the Muire. The Allied army was thus on the south bank of the Vesle, while Rheims itself is on the north bank.
Marmont's forces arrived first. Napoleon decided to wait until Ney arrived, a move that helped convince St. Priest that he still only faced a small force. When the French did attack the Allies were routed. Their line was broken in half, and St. Priest was quickly forced to order a retreat. He was then mortally wounded by a salvo from the Guard Artillery, and the retreat turned into a rout. Elsewhere the French got a bridge across the Vesle, and began to threaten the Allied line of retreat north towards Laon. The surviving Allied troops fled south away from the disaster.
Napoleon entered Rheims at 1am on 14 March, and was greeted as a liberating hero. The city was lit up, and some accounts have the fighting carried out by lantern light.
The French lost around 700-800 men in this battle. The Allies probably lost 700-800 dead, 1,500-1,600 wounded, 2,500-3,500 prisoners and 11-14 guns as well as part of the Russian bridging train.
The fall of Rheims caused a brief panic in the Allied camps. Blucher withdrew back to Laon, while Schwarzenberg stopped his advance along the Aube and Seine. However Napoleon had already rejected the last Allied peace terms, so the war continued.
Despite this success the end was now near for Napoleon. His attempts to defeat the Allied armies in battle had failed to lift the threat to Paris, and so he decided to launch his armies into their rear areas, where he could join up with troops from his besieged fortresses and hopefully force Schwarzenberg and Blucher to pull back from Paris. Before moving east he attempted to inflict another defeat on Schwarzenberg by hitting what Napoleon believed to be his rearguard at Arcis-sur-Aube (20-21 March 1814). Instead, just as at Craonne and Laon, Napoleon ran into one of the main Allied armies and was luck to escape with his army intact. Only Schwarzenberg reluctance to attack on the second day of the battle saved the French from a heavy defeat. Napoleon continued with his plan, and moved east from Arcis to St. Dizier. Unfortunately for him the Allies captured a copy of his plans, and decided to ignore him. Schwarzenberg decided to head north to join up with Blucher and then head for Paris. Napoleon had left Marmont and Mortier to watch Blucher and defend Paris, but on 25 March 1814 they were defeated by Schwarzenberg at La-Fere-Champenoise. Many of Napoleon's battles earlier in the campaign had been nearer to Paris than this, but this time the Emperor wasn't present, and he was unable to intervene as the Allies advanced on his capital. Although the outnumbered defenders of Paris managed to hold the Allies up at Montmartre (30 March 1814), but that night they agreed to surrender Paris, and early on 31 March the garrison marched out and the Allies moved in. Many of Napoleon's marshals made it clear that they were no longer willing to fight on, and a few days later the Emperor abdicated for the first time.