The position was an excellent one for defence, considering the range of artillery and infantry fire of that date, and would have fully compensated for the slight advantage of numbers which Napoleon possessed, had the quality of the two armies been equal. They were substantially equal in infantry, a little under 50,000 each: but Napoleon had 15,000 cavalry as against 12,000, and many more guns, 246 to 156. Wellington however could not place much reliance on the Dutch-Belgian contingent, nearly 18,000 strong. The sympathies of many of them were with the French, and none of them had seen service, unless perchance in the emperor's army before his first abdication. Consequently the duke thought it expedient to distribute these troops among the English and Germans: he would obviously have done better, assuming that he was convinced of the necessity of leaving a strong body at Hal, to have posted none but Dutch and Belgians there, the more so as the command at Hal was entrusted to a Dutch prince, and to have had Colville's English on the field of Waterloo.
Wellington's army was distributed as follows, the front being generally behind the country road from Wavre. On the extreme left, which was unprotected by any natural features, were two brigades of light cavalry, Vivian's and Vandeleur's. Next came two Hanoverian brigades, Vincke's and Best's: then, a little further back, Pack's brigade consisting of the 1st, 42nd, 44th and 92nd British regiments. To the right of Pack, extending as far as the high road, was Kempt's brigade, comprising the 28th, 32nd, 79th and 1st battalion 95th. A Dutch-Belgian division was posted in front of this, the left half of the line. One brigade occupied the hamlet and farms that partially protected the front: the other, Bylandt's, was posted on the slope facing the south, where it was exposed to crushing fire from the French artillery, which so shook it that early in the battle it gave way, retired in confusion over the ridge, and could be used no more. This was almost the only mistake made by Wellington in the actual tactics of the battle: one other only can be cited against him, and that as it happened was in the same part of the field. The farm of La Haye Sainte, a large courtyard with solid walls and buildings round it, just on the high road and protecting the very centre of the whole position, was garrisoned but slightly, and was not prepared for defence, nor were the troops in it supplied, as they should have been, with ample stores of ammunition. La Haye Sainte was garrisoned from one of two German brigades, Ompteda's and Kielmansegge's, which lay immediately to the right of the high road. Next to them came Sir Colin Halkett's English, these three brigades forming Count Alten's division. To the right, more or less behind Hougomont, and furnishing a great part of its garrison, was posted General Cooke's division, consisting of Maitland's and Byng's brigades of guards. To the right of the guards, Mitchell's English brigade lined the cross road which runs north-west from near Hougomont to Braine-la-Leud, a couple of miles off, where a Belgian division was posted; they thus guarded the right of the position. In rear of the guards lay Clinton's division, one brigade of which, Adam's, played a very important part in the last stage of the battle: this division was well placed to act as a reserve for any part of the line. The regular reserve of about 10,000 men, of which over one-third were cavalry, was placed a mile or so in rear of the centre. The rest of the cavalry formed a second line in rear of the right and centre, the heavy cavalry, Somerset's brigade of guards and Ponsonby's Union brigade (the Royal Dragoons, Scots Greys, and Inniskillings), being close to right and left of the high road. The artillery was not massed together after the fashion which has generally prevailed in recent wars; the field batteries were distributed along the front, in the proportion of about one battery to each brigade, and the horse artillery was similarly joined to the cavalry. It remains to add that Hougomont had been very fully prepared for defence. The entire property, about one-third of a mile square, was generally enclosed only with hedges: but the farmyard and garden adjoining the house in the north-west corner had good walls: and the orchard at the north-east had also a wall on the north, which enabled the defenders to drive the French out of the orchard again, when once they penetrated to it.