An extract on #carporn
The French right, left, and centre had all now failed. The last cohesive French force consisted of two battalions of the Old Guard stationed around La Belle Alliance; they had been so placed to act as a final reserve and to protect Napoleon in the event of a French retreat. He hoped to rally the French army behind them, but as retreat turned into rout, they too were forced to withdraw, one on either side of La Belle Alliance, in square as protection against Coalition cavalry. Until persuaded that the battle was lost and he should leave, Napoleon commanded the square to the left of the inn. Adam's Brigade charged and forced back this square, while the Prussians engaged the other.
As dusk fell, both squares withdrew in relatively good order, but the French artillery and everything else fell into the hands of the Prussian and Anglo-allied armies. The retreating Guards were surrounded by thousands of fleeing, broken French troops. Coalition cavalry harried the fugitives until about 23:00, with Gneisenau pursuing them as far as Genappe before ordering a halt. There, Napoleon's abandoned carriage was captured, still containing an annotated copy of Machiavelli's The Prince, and diamonds left behind in the rush to escape. These diamonds became part of King Friedrich Wilhelm of Prussia's crown jewels; one Major Keller of the F/15th received the Pour le Mrite with oak leaves for the feat. By this time 78 guns and 2,000 prisoners had also been taken, including more generals.
There remained to us still four squares of the Old Guard to protect the retreat. These brave grenadiers, the choice of the army, forced successively to retire, yielded ground foot by foot, till, overwhelmed by numbers, they were almost entirely annihilated. From that moment, a retrograde movement was declared, and the army formed nothing but a confused mass. There was not, however, a total rout, nor the cry of sauve qui peut, as has been calumniously stated in the bulletin.
In the middle of the position occupied by the French army, and exactly upon the height, is a farm (sic), called La Belle Alliance. The march of all the Prussian columns was directed towards this farm, which was visible from every side. It was there that Napoleon was during the battle; it was thence that he gave his orders, that he flattered himself with the hopes of victory; and it was there that his ruin was decided. There, too, it was that, by happy chance, Field Marshal Blcher and Lord Wellington met in the dark, and mutually saluted each other as victors.
Other sources agree that the meeting of the commanders took place near La Belle Alliance, with this occurring at around 21:00.