War of the Sixth Coalition
Coalition armies march on ParisParis, France
Thus after six weeks fighting the Coalition armies had hardly gained any ground. The Coalition generals still hoped to bring Napoleon to battle against their combined forces. However, after Arcis-sur-Aube, Napoleon realised that he could no longer continue with his current strategy of defeating the Coalition armies in detail and decided to change his tactics. He had two options: he could fall back on Paris and hope that the Coalition members would come to terms, as capturing Paris with a French army under his command would be difficult and time-consuming; or he could copy the Russians and leave Paris to his enemies (as they had left Moscow to him two years earlier). He decided to move eastward to Saint-Dizier, rally what garrisons he could find, and raise the whole country against the invaders. He had actually started on the execution of this plan when a letter to Empress Marie-Louise outlining his intention to move on the Coalition lines of communications was intercepted by Cossacks in Blücher's army on 22 March and hence his projects were exposed to his enemies.
The Coalition commanders held a council of war at Pougy on the 23 March and initially decided to follow Napoleon, but the next day Tsar Alexander I of Russia and King Frederick of Prussia along with their advisers reconsidered, and realising the weakness of their opponent (and perhaps actuated by the fear that Duke of Wellington from Toulouse might, after all, reach Paris first), decided to march to Paris (then an open city), and let Napoleon do his worst to their lines of communications.
The Coalition armies marched straight for the capital. Marmont and Mortier with what troops they could rally took up a position on Montmartre heights to oppose them. The Battle of Paris ended when the French commanders, seeing further resistance to be hopeless, surrendered the city on 31 March, just as Napoleon, with the wreck of the Guards and a mere handful of other detachments, was hurrying across the rear of the Austrians towards Fontainebleau to join them.