We can have no hesitation in admitting that if the Prussians had been driven in the direction of the Meuse as the result of the battle, they could not have afforded aid to the English on the 18th of June. But we can hardly believe that if Napoleon had destroyed their Ist and IId Corps, which he expected would be the result of his plan of battle, the Prussians could possibly have afforded any further assistance to the English. Still, while the decision of the Prussian generals after the battle to maintain their communication with the Duke of Wellington, and to come to his assistance at Waterloo with their whole army, was not arrived at merely or chiefly because the two corps which had been beaten at Ligny were able to fall back in a northerly direction instead of in an easterly direction, in retiring from the field of battle,[383] it is certainly true that this fact did make the task easier of accomplishment; it saved time, also. At the same time, it did not affect in any way the risk involved in the operation,—that of renouncing for the time being their line of supplies. 3. We have seen that Napoleon believed that Ney’s intervention, which, as we have seen, might have occurred at the moment when the Prussian centre was being pierced, would have gained him a great victory. But Clausewitz[384] asks: “Why was it inevitable that 10,000 men in the rear of the strong Prussian army of 80,000 men, in an open country, where one can see on all sides, should bring about its complete overthrow?” In other words, Napoleon was not warranted (so Clausewitz contends) in expecting such a decisive success, even if Ney should send 10,000 men down the Namur road. But Clausewitz has not in his question, above quoted, put the case quite fairly. The question which Napoleon considered was this:—What would in all probability be the effect upon two Prussian corps, numbering at the commencement of the action not over 63,000 men, attacked vigorously for three or four hours, subjected during that time to a most destructive fire of artillery, reduced by casualties to a force not greatly exceeding 50,000 men, assailed in front by over 20,000 fresh troops in addition to their opponents of the last few hours, forced to make a precipitate retreat by having their connection with the rest of their army broken,—what would be the effect upon them at this moment of an unexpected and vigorous attack in rear of 10,000 fresh troops? Napoleon thought and said, that, in his judgment, the result would be the total rout of the two corps, the capture of all their guns and perhaps half of their men. It is probable that he was right in his opinion. 4. But how far was Napoleon warranted in expecting aid from Ney?