It is quite true, that this last remark shows, as several writers[304] have pointed out, that the Emperor was to a considerable extent mistaken on this morning of the 16th in his apprehension of the situation. But it is an error to take these letters as if they were written for the purpose of giving Napoleon’s estimates of the probabilities; they are rather instructions in the event of the occurrence of not impossible contingencies. The fact in the case was just this,—the main army was about to make a forward movement against the Prussians; if they were found to be in force and offered battle, the result of this battle would of course settle everything; but if they should retire, instead of offering battle, they must be followed, and that involved the separation of the French army into two unequal portions. Hence it was very desirable to inform Ney, from whom in this event the right wing and reserves would march away, about how far the Prussians would be followed, and, especially to enjoin upon him, in case the Emperor should deem it safe to leave the care of the Prussians to Grouchy, and should himself retrace his steps, and, with his Guard, join the left wing, to be ready to march on Brussels at an instant’s notice. It must be noted, too, that these letters, especially when taken in connection with the formal orders of Soult to the two Marshals, show how absolutely Napoleon adhered to his original conception of the campaign, as we have before described it. To attack the Prussians first,—to follow them up for a considerable distance, so as to be assured of the direction which their retreat was taking,—and then, and only then, to return to the Brussels road and advance on the English,—such was the programme marked out in the two letters to Ney and Grouchy. We shall have occasion to refer to this in another place.