The Emperor had been the first, as early as midday, to descry with his field-glass, on the extreme horizon, something which had attracted his attention. He had said, “I see yonder a cloud, which seems to me to be troops.” Then he asked the Duc de Dalmatie, “Soult, what do you see in the direction of Chapelle-Saint-Lambert?” The marshal, levelling his glass, answered, “Four or five thousand men, Sire; evidently Grouchy.” But it remained motionless in the mist. All the glasses of the staff had studied “the cloud” pointed out by the Emperor. Some said: “It is trees.” The truth is, that the cloud did not move. The Emperor detached Domon’s division of light cavalry to reconnoitre in that quarter.

Bülow had not moved, in fact. His vanguard was very feeble, and could accomplish nothing. He was obliged to wait for the body of the army corps, and he had received orders to concentrate his forces before entering into line; but at five o’clock, perceiving Wellington’s peril, Blücher ordered Bülow to attack, and uttered these remarkable words: “We must give air to the English army.”