In the Battle of Wavre was the final major military action of the of the Hundred Days campaign and the Napoleonic Wars. It was fought on 18-19 June 1815 between the Prussian rearguard under the command of General Johann von Thielmann and three corps of the French army under the command of Marshal Grouchy. In the battle, a Prussian rearguard was pushed back by a much larger French force, but resisted for long enough for Field Marshal Blücher's main force to move to help Wellington defeat Napoleon at Waterloo.
Following defeat at the Battle of Ligny two days earlier, the Prussian army retreated north in some disorder, exposing the eastern flank of Wellington's allied force at Quatre Bras, who also retreated northward, to a defensive position at Waterloo. Napoleon moved the bulk of his army off in pursuit of Wellington, and sent Grouchy in pursuit of the retreating Prussians with the right wing (aile droite) of the Army of the North (L'Armée du Nord), a force consisting of 33,000 men and 80 guns
Grouchy was slow in taking up the pursuit after Ligny, which allowed Blücher to fall back largely unmolested to Wavre, regroup his army, and then execute a flank march with three of his four corps to join up with Wellington's Anglo-Allied army at Waterloo. The remaining corps, Thielmann's III Prussian Corps of 17,000 men and 48 guns, was left at Wavre as a rearguard. Thielmann's main force occupied Wavre and Bierges while a small flank guard occupied Limal.
General Vandamme opened the Battle of Wavre at 4 pm unlimbering 3 batteries, then moved Habert's division in an attempt to take the bridges by quick assault. Marshal Grouchy, having just received Marshal Soult's order to move against Wavre, moved Exelmans' cavalry with an infantry battalion against the bridge at Bas-Wavre while Lefol's division moved against the bridge at Bierges. The fusilier battalion of the 1st Kurmark Landwehr Regiment defended the Bierge bridge by removing timbers from it under French fire and countercharging any attempt to repair it. The Kurmarkers held the right bank of the stone bridge at Wavre for some time, forcing Vandamme's troops to waste precious time taking it. Once this was done the French rushed across the bridge and straight into a vicious street fight. A battalion of the 11th Kurmark moved to support the 1st and threw the French back across the bridge. A French renewed assault penetrated further down the same street, only to be ambushed from side streets by the fusiliers of the 1st and 30th regiments using point blank musketry, and a bayonet charge sent the French scrambling across the bridge again. This seesaw battle would continue throughout the night. Later attacks by the French upon Bas-Wavre met with no more success. The Prussians assigned another battalion and three guns to the bridge. Prussian hussars were assigned to cover a wooden bridge south of Bas-Wavre. The attacks by Lefol upon the bridge of Bierges had no more success, being hampered by muddy ground and the tough defense of Prussian 31st Regiment supported by II Musketeer/6th Kurmark Landwehr and a horse battery.
Marshal Soult's 1 pm letter ordering Grouchy to move quickly to join Napoleon and to attack Bulow arrived after 6 pm. Grouchy at once began gathering additional divisions and headed to Limale, arriving at 11:00 pm, where he found that Pajol's cavalry had forced the bridge there. Prussian scouting cavalry noticed the strong French columns moving to Limale and the Prussian 12th Brigade moved covering forces to the area. The Prussians made a bayonet charge in an attempt to retake Limale but without success. Night closed the major actions of the battle of Wavre, although outposts fired on each other all night.
Grouchy was across the Dyle, but meanwhile the Battle of Waterloo by this time had been irrevocably lost, and the remnants of the Armėe du Nord were streaming south towards the safety of French territory.
Fighting renewed in the early hours. The forest south of Limale was forced by 9 am. Thielmann elected to retreat, as the campaign had been decided by the fighting elsewhere. The definitive report of the victory at Waterloo reached Thielmann at 10 am as the retreat started. Grouchy, watching the retreat, was beginning his planned move upon Brussels when the news reached him at 10:30 am that Napoleon had been defeated. Though in shock, Grouchy realised he was in danger of being trapped and his entire command destroyed. He at once had Exelmans move his cavalry to secure the bridges and began a retreat by forced marches that would take him to the fortress at Namur.