On 22 February 1814, Schwarzenberg with nearly 150,000 Allied troops faced Napoleon with half that number at Troyes. Because bad news arrived from the south and the Allied army was poorly supplied, but mainly because he believed that he was outnumbered, Schwarzenberg ordered a retreat that evening. Disappointed that no battle was going to be fought, Blücher proposed that his army separate from the main army and operate to the north. To this Schwarzenberg agreed and Blücher's 53,000 soldiers began moving northwest. When he realized that the Prussian field marshal's army was headed for Paris, Napoleon left 42,000 troops under Marshal Jacques MacDonald to contain Schwarzenberg and marched after Blücher with 35,000 men. An additional 10,000 soldiers under Marshals Auguste de Marmont and Édouard Mortier stood between the Prussian field marshal and Paris.
Marmont and Mortier blocked Blücher's advance on 28 February when they defeated Friedrich von Kleist's corps in the Battle of Gué-à-Tresmes. The following day, Blücher again failed to push the reinforced French out of his path, but time had run out. On 2 March the Prussian field marshal realized that Napoleon was following him and decided to retreat to the north bank of the Ourcq River. He knew that Wintzingerode's Russians and Bülow's Prussians were nearby and hoped to join them soon. The premature surrender of Soissons allowed Blücher to more easily cross to the north bank of the Aisne River on 3–4 March. By this time Napoleon knew that Wintzingerode had joined Blücher, giving him at least 70,000 men to oppose 48,000 French troops. However, the French emperor believed that Bülow was still well to the north near Avesnes-sur-Helpe.
In fact, Blücher may have had as many as 110,000 troops by this time. They were distributed as follows – Russians: Wintzingerode (30,000), Louis Alexandre Andrault de Langeron (26,000), Fabian Gottlieb von Osten-Sacken (13,700); Prussians: Bülow (16,900), Kleist (10,600), Ludwig Yorck von Wartenburg (13,500). For his part, Napoleon had 34,233 troops on 2 March while Marmont and Mortier had been reinforced to 17,000 men but lost possibly 3,000 casualties in the week before Craonne. Yet, Napoleon hoped to get to Laon before Blücher's army arrived there. On 5 March, Napoleon was at Fismes from where he hoped to move straight north to Laon. Since he lacked a pontoon bridge to cross the Aisne, the French emperor directed his forces to move northeast to Berry-au-Bac where there was a stone bridge. Berry-au-Bac was on the direct road from Reims to Laon. On this day, Napoleon ordered Jan Willem Janssens at Mézières to gather up the Ardennes garrisons and operate in Blücher's rear areas. Janssens promptly obeyed and the movements of his troops threw a scare into the Allies.
At 5:00 am on 5 March, Guard cavalry divisions under Pierre David de Colbert-Chabanais and Louis Marie Levesque de Laferrière surprised and captured Reims and its Allied garrison. Napoleon ordered Étienne Marie Antoine Champion de Nansouty to seize Berry-au-Bac with a cavalry force consisting of Rémi Joseph Isidore Exelmans' division and Louis Michel Pac's brigade. Nansouty's troopers overran some Russian cavalry and captured 200 men and two guns, but the main prize was their seizure of the bridge. Louis Friant's 1st Old Guard Division and Claude Marie Meunier's 1st Young Guard Division crossed and occupied positions as far north as Corbeny. From 3:00–6:00 pm on 5 March, Marmont and Mortier tried to capture Soissons from its Russian garrison, but were repulsed. The Russians sustained 1,056 casualties, while the French lost 800–900 men. Another source calculated French losses as 1,500 men.
Blücher realized that Napoleon was trying to reach Laon by the Reims road. He sent Bülow and his wagon trains back to Laon. The Prussian commander began to shift his other forces to the northeast. By 6 March Napoleon had 30,500 men near Berry-au-Bac. He planned to send an advanced guard north toward Festieux, but needed to make sure of Blücher's intentions. During the day of 6 March, Meunier's division encountered Russian forces near Vauclair Abbey (Vauclerc) while two battalions of the Old Guard were needed to flush out Craonne's Russian defenders. At first Blücher directed his army to concentrate near Craonne, but he decided that position was too cramped for his 90,000 men. He also heard that French cavalry were advancing north on the Reims road. Changing plans, Blücher planned to assemble 10,000 cavalry and 60 horse artillery guns under Wintzingerode and send it toward Festieux. Wintzingerode's force consisted of 5,500 of his own horsemen plus all of the reserve cavalry belonging to Langeron and Yorck. Blücher ordered Wintzingerode's infantry, commanded by Vorontsov, to remain behind and directly oppose Napoleon's army.
Allied corps commanders
Russian General Fabian von Osten-Sacken
Russian General Louis Andrault de Langeron
Prussian General Ludwig Yorck
Prussian General Friedrich von Bülow
Prussian General Friedrich von Kleist
Russian General Ferdinand von Wintzingerode
French corps commanders
Marshal Auguste de Marmont
Marshal Claude Perrin Victor
General of Division Augustin Belliard (replaced Grouchy)
General of Division Étienne de Nansouty