Napoleon spent three days at Reims following his victory. With Blücher still recovering from sickness, Gneisenau did not trouble the French during that time. The French emperor sent Ney to seize Châlons-sur-Marne, which was done without opposition. Ney was joined by Jan Willem Janssens who gathered 3,000 men from the Ardennes garrisons. Meanwhile, Schwarzenberg's army advanced perilously close to Paris. Napoleon's problem was to lure the Allied army away from Paris. He decided to leave Marmont and Mortier with 21,000 soldiers to watch Blücher and move south toward Arcis-sur-Aube to threaten Schwarzenberg's supply line. The Battle of Arcis-sur-Aube was fought on 20–21 March 1814.