Villars had received intelligence of Marlborough’s march only two hours after he had started, but he was so thoroughly bewildered by the Duke’s intricate manœvres that he did not awake to the true position until three hours later. Then, quite distracted, he put himself at the head of the Household Cavalry and galloped off at full speed. So furiously rode he that he wore down all but a hundred of his troopers and pushed on with these alone. But even so Marlborough was before him. At eight o’clock he crossed the lower causeway at Aubanchœuil-au-bac and passing his cavalry over the Sensée barred the road from the west by the village of Oisy. Presently Villars, advancing reckless of all precautions, blundered into the middle of the outposts. Before he could retire, his whole escort was captured, and he himself only by miracle escaped the same fate. The Marshal now looked anxiously for the arrival of his main body of horse; but the Allied infantry had caught sight of the French on the other side of the Sensée, and, weary though they were, had braced themselves to race them for the goal. Nevertheless the severity of the march and the burden of their packs began to tell heavily on the foot. Hundreds dropped down unconscious, and many died there and then, but they were left where they lay to await the arrival of the rearguard; for no halt was called, and each regiment pushed on as cheerfully as possible with such men as still survived. Thus they were still ahead of the French when they turned off to the causeway at Arleux, and, Marlborough having thrown additional bridges over the Sensée, they came quickly into their positions. The right wing of infantry crossed the river about four o’clock in the afternoon, having covered close upon forty miles in eighteen hours; and by five o’clock the whole force was drawn up between Oisy and the Scheldt within striking distance of Arras, Cambrai, and Bouchain. So vanished the ne plus ultra of Villars, a warning to all generals who put their sole trust in fortified lines.