Like Hougoumont and Papelotte, this beautiful farm was transformed into a fortress by the Allied army, garrisoned by six companies of the King's German Legion, which were later reinforced by two companies of Nassau troops. From 2pm onwards they were subjected to furious attack and were finally forced to withdraw. The French finallly captured the farm but incurring such a loss of lives and time that they could not exploit their success. Two plaques on the walls commemorate the fierce struggle that took place here.

 La Haie Sainte in Wellington's centre had also been the centre of heavy fighting all day. This farm was garrisoned by Major George Baring and the riflemen of the 2nd Light Battalion, King's German Legion. They were supported to the east in a sandpit by three companies of the 95th Rifles ('les coquins verts' or 'the rascals in green' as the French liked to refer to them). The farm had been under constant attack from the French since 13.00pm and had been a thorn in the French side as first D'Erlon's attack and then Ney's had had to pass by the Allied position.

At 18.00pm when the French cavalry attack to the west had ground to a halt, the French made a last determined effort to take the farm. La Haie Sainte was on fire, their ammunition was virtually spent and only about 40 of the original 400 defenders were still mobile. With French artillery firing at point-blank range, the French infantry made a final successful assault. This was a dangerous moment for Wellington, but he reinforced his centre, leading some battalions there personally.

With the Prussian army now arriving at Plancenoit, the moment passed and Napoleon had to dispatch the Young Guard to deal with the Prussian threat to his right flank. Once Blucher's troops had been able to concentrate, they immediately attacked Plancenoit, La Haie and Papelotte. The Allies had now achieved what Napoleon had been determined to prevent, the Anglo-Dutch and Prussian armies fighting on one battlefield against him. Indeed, Wellington had observed at 16.20pm that "The battle is mine and if the Prussians arrive soon there will be an end of the war".