Did Napoleon retire, he would retire before forces half as large again as his own, and destined to grow to double his own within a few hours. His retirement would leave Grouchy to certain disaster. Politically, retreat was still more hopeless. He himself would re-enter France defeated, with, at the most, half the strength that had crossed the frontier three days before. He would so re-enter France--the wealthier classes of which watched his power, nearly all of them with jealousy, most with active hate--surrounded by general officers not ten of whom, perhaps, he could sincerely trust, and by a whole society which supported him only upon the doubtful condition of victory. Such a retirement was ruin. It was more impossible morally even than it was impossible physically, under the conditions of the field. Therefore it was that, under conditions so desperate, with his battle lost if ever battle was, the Emperor yet attempted one ultimate throw, and in this half-hour before the sunset sent forward the Guard. In those solemn moments, wherein the Imperial Guard formed for their descent into that hollow whose further slope was to see their last feat of arms, Ziethen, with the First Prussian Corps, pressed on into the far corner the field of battle. At the far end of the long ridge of the Mont St Jean, more than a mile away, this last great body and newest reinforcement of the Emperor's foes had emerged from the walls and thickets of Smohain and, new to the fighting, was already pushing in the weary French line that had stood the carnage of six hours. It was not enough that the Fourth Prussian Corps should have determined the day already with its 30,000 come up from the east against him; now the foremost battalions of the First coming up from the north were appearing to clinch the matter altogether. It was under such conditions of irretrievable disaster that Napoleon played for miracle, and himself riding slowly down the valley at the head of his comrades and veterans, gave them over to Ney for the final attack against Wellington's line which still held the opposing slope. It was then, at the moment when Ziethen and the men of the First Prussian Army Corps began to press upon the north-eastern angle of the fight, and were ready to determine it altogether, that the Guard began its ponderous thrust up between Hougomont and La Haye Sainte, to the west of the Brussels road. Up that fatal hill, which had seen the four great cavalry charges, and more recently the breaking of the Second Corps, the tall men, taller for the bearskins and the shouldered musket, the inheritors of twenty-two victorious and now immortal years, leant forward, advancing. To the hanging smoke of the cannon in the vale was added the rising mist of evening; and when the furious cannonade which was to support their attack had ceased with their approach to the enemy's line, a sort of silence fell upon the spectators of that great event. The event was brief.