Battle of Wavre The Battle of Wavre was the final major military action of the Hundred Days campaign and the Napoleonic Wars . It was fought on 18 – 19 June 1815 between the Prussia n rearguard under the command of General Johann von Thielmann and three corps of the French army under the command of Marshal Grouchy . A blocking action , this battle kept 33 , 000 French soldiers from reaching the battle at Waterloo . This battle helped the Allied forces defeat the French army there . Background . 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 northwards , 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 . The French units in the order of battle were : 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 . Grouchy ' s positions . Marshal Grouchy was in Gembloux with III Corps commanded by General Vandamme and IV Corps commanded by General Gerard . The 4th Cavalry Division , commanded by Pajol , and the 21st infantry division , under Teste ( from Lobau ' s corps ) , formed the remainder of his force . Reconnaissance by Pajol ' s horsemen during the 17 June found that the Prussians had left Namur . Final movements . At around 06 : 00 of 18 June 1815 Grouchy reported to Napoleon that the Prussians had left Tourinnes by marching all night . He further reported that he was moving on Wavre with all haste . At 10 : 00 Grouchy reported to Napoleon that the Prussian I , II , and III Corps were marching in the direction of Brussels , and that Prussian officers were talking of joining Wellington to offer battle to the French army . His despatch included a Prussian requisition form by way of proof . He noted that by attacking and standing at Wavre , he could block the Prussians from intervening against the rest of the French army . At 11 : 30 , Grouchy and his corps commanders heard in the distance the noise from the Grand Battery as the Battle of Waterloo started . Grouchy ' s corps commanders , especially Gérard , suggested that they should " march to the sound of the guns " Grouchy , however , had written and verbal orders from Napoleon to march on Wavre and to engage the Prussians there , and knew that Marshal Ney had been taken to task by Napoleon two days earlier for not following orders at the Battle of Quatre Bras . Grouchy therefore declined to follow his subordinates ' suggestion , pointing out that Napoleon had more than enough force to deal with Wellington . Minutes after this conversation , Exelmans reported strong Prussian positions from Wavre . At 13 : 00 , elements of Exelmans ' cavalry were in contact with the Prussian 14th Brigade ’ s rear guard . Further argument was ended by the arrival at 16 : 00 of another order from Napoleon , repeating the instruction to Grouchy to attack the Prussians before him . The race to the Dyle . The battle to come now hinged on control of the crossings over the river Dyle . Every passing moment would see more Prussian brigades passing through Wavre on the way to Waterloo ; by 13 : 30 7th and 8th Brigades passed through Wavre and would next be seen at 19 : 30 pushing an Imperial Guard unit out of the woods south of Plancenoit on the Waterloo battlefield . Battle . Late in the afternoon of 18 June , as Napoleon was heavily engaged against Wellington at Waterloo , Grouchy , commanding the corps of General Gérard and General Vandamme , prepared to attack the Prussian forces confronting him over the River Dyle between the towns of Wavre and Limal . General Vandamme opened the Battle of Wavre at 16 : 00 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 , ordered 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 counter - charging 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 2nd Kurmark Landwehr Regiment moved to support the 1st and threw the French back across the bridge . A renewed French assault penetrated further down the same street , only to be ambushed from side streets by the fusiliers of the 1st Kurmark Landwehr and 30th Line Infantry Regiments using point blank musketry . A bayonet charge sent the French scrambling across the bridge again . This see - saw battle would continue throughout the night . Later attacks by the French upon Wavre met with no more success . The Prussians assigned another battalion and three guns to the bridge . The bridge at Bas - Wavre had been destroyed by the Prussians . The attacks by Lefol upon the bridge of Bierges had no more success , being hampered by muddy ground and the tough defense of the Prussian 31st Line Infantry Regiment supported by the 2nd battalion of the 6th Kurmark Landwehr Regiment and a horse battery . Three small battalions and three squadrons of cavalry under Stengel were to guard a bridge to the west at Limal . Marshal Soult ' s 13 : 00 letter ordering Grouchy to move quickly to join Napoleon and to attack Bulow arrived after 18 : 00 Grouchy at once began gathering additional divisions and headed to Limal , arriving at 23 : 00 , where he found that Pajol ' s cavalry had forced the bridge there . Prussian scouting cavalry noticed the strong French columns moving to Limal and the Prussian 12th Brigade moved covering forces to the area . The Prussians made a bayonet charge in an attempt to retake Limal but without success . Night closed the major actions of the battle of Wavre , although outposts fired on each other all night . At approximately 20 : 00 the French attack at Waterloo was lost as its left , center , and right positions collapsed within a few minutes of each other . 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 Limal was forced by 09 : 00 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 : 00 as the retreat started . Grouchy , watching the retreat , was beginning his planned move upon Brussels when the news reached him at 10 : 30 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 back to Paris . Conclusion . While the battle ended in a French victory , with the Prussians in retreat and Grouchy firmly athwart Prussian lines of communication to the east , this situation lasted a total of 30 minutes and thus it proved hollow . The Prussians held their ground long enough to allow Blücher ' s transfer of 72 , 000 troops to Wellington ’ s aid at Waterloo . Thus to the Prussians , the battle was a strategic success , as it contributed to a decisive victory at Waterloo . In addition , the Prussian rearguard of 17 , 000 troops tied down 33 , 000 French troops that could have otherwise taken part at Waterloo .