Following defeat at the Battle of Ligny two days earlier, the Prussian army retreated north in good order and formed up at Wavre.

Wellington's Anglo-allied army won a tactical victory at Quatre Bras, but had been unable to come to the aid of the Prussians at Ligny and retreated northwards, to a defensive position at Waterloo.

[2] The French units in the order of battle were:[a] Grouchy was slow in taking up the pursuit after Ligny, which allowed Prince 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.

Blücher had ordered Thielmann to defend the position of Wavre in the event of Marshal Grouchy advancing in force, or, if otherwise, to follow the main Prussian army in the direction of Couture-Saint-Germain and the battlefield of Waterloo.

[8] All the brigades (the 9th, 10th, 11th, and 12th) of the Prussian III Corps (Thielmann's), had, at that time, received the order to commence the general movement to the right (west).

[10] The town of Wavre is situated on the left (north) bank of the Dyle, having a suburb on the opposite side of the river, with which it was then connected by two stone bridges.

The heights on the right bank are generally more elevated, but those on the left have steeper declivities, and offer a greater command of the river and its passages.

The great number of hollow ways forms a prominent feature in the vicinity, and these, being in a miry state from the rain, were unfavourable to the progress of troops passing through them.

[13] Thielmann intended that the 9th Brigade should be posted in rear of this general disposition of his troops, so that its services might be made available according as circumstances might require; but through some misunderstanding in the transmission of the order, General Borcke was induced, after having moved along the Brussels road until near La Bawette, thence to turn off to his left, and continue his march, according to his original instructions in the direction of Froidmont,[f] Bourgeois, and Saint-Lambert, towards Couture-Saint-Germain; being under the impression that the whole corps had already commenced this march, in pursuance of the general plan, and that his brigade was destined to cover the movement.

[17] In the opinion of William Siborne a contemporary British historian, Thielmann's position was certainly a very favourable one, and the occupation of it was arranged with great skill.

Thielmann therefore limited the occupation of the town and of the line of the river to the number of light troops that might be sufficient for sustaining any sudden assault, taking care to have support close at hand for that purpose.

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.

[19] 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.

Marshal Soult's 13:00 letter ordering Grouchy to move quickly to join Napoleon and to attack Bülow 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.

Grouchy was by then across the Dyle, but meanwhile the remnants of the Armėe du Nord were streaming south towards the imagined safety of French territory.

[24] Grouchy, watching the Prussian retreat, was beginning his planned move upon Brussels when the news reached him at 10:30 that Napoleon had been defeated.

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.