This task was accomplished through pouring rain, by unpaved lanes and through intolerable mud, over a distance of close on seventeen miles for the hardest pushed of the troops, and not less than thirteen for those whom the accident of position had most spared. The greater part of the Fourth Corps had spent the first night in the open; all of it had spent the second night upon the drenched ground. Upon the _third_ day, the Sunday of Waterloo, this force, though it lies furthest from the field of Waterloo of all the Prussian forces, is picked out to march first to the aid of Wellington, because it as yet has had no fighting and is supposed to be "fresh." On the daybreak, therefore, after bivouacking in that dreadful weather, Bulow's force is again upon the move. It does not get through Wavre until something like eight o'clock, and the abominable conditions of the march may be guessed from the fact that its centre did not reach St Lambert until one o'clock, nor did the last brigade pass through that spot until three o'clock. Down the steep ravine of the Lasne and up on the westward side of it was so hard a business that, as we have seen, the brigades did not begin to debouch from the woods at the summit until after four o'clock. It was not until after five o'clock that the last brigade, the 14th, had come up in line with the rest upon the field of Waterloo, having moved, under such abominable conditions of slow, drenched marching, another fifteen miles. In about forty-eight hours, therefore, this magnificent piece of work had been accomplished. It was a total movement of over fifty miles for the average of the corps--certainly more than sixty for those who had marched furthest--broken only by two short nights, and those nights spent in the open, one under drenching rain. The whole thing was accomplished without appreciable loss of men, guns, or baggage, and at the end of it these men put up a fight which was the chief factor in deciding Waterloo. Such was the supreme effort of the Fourth Prussian Army Corps which decided Waterloo. There are not many examples of endurance so tenacious and organisation so excellent in the moving so large a body under such conditions in the whole history of war. * * * * * When the Fourth Prussian Corps debouched from the Wood of Fischermont and began its two-mile approach towards his flank, Napoleon, who had already had it watched by a body of cavalry, ordered Lobau with the Sixth French Army Corps, or rather with what he had kept with him of the Sixth Army Corps, to go forward and check it.