Meanwhile Blucher had been doing his best. The country between Wavre and the battle-field is formed in rounded hills and deep hollows, traversed by mere lanes, and the soil was soft and miry from the heavy rain. At noon Bulow's leading division reached St. Lambert, the highest point on the road, whence the battle-field was visible at some four miles' distance: Napoleon within an hour ascertained that they were Prussians, and too late recognising his danger, sent off a useless despatch to summon Grouchy to his aid. He also sent some cavalry to meet the Prussians, but it was not for at least two hours more that the latter came into action. The roads naturally grew worse with use, and the artillery could scarcely be moved at all. It needed all the energy of hatred which inspired the whole Prussian army, it needed all the pressure Blucher in person could put on the soldiers, for the task to be accomplished. "Kinder, ihr wollt doch nicht dass ich wortbrüchig werden soll," was the old marshal's often repeated appeal: and Englishmen ought never to forget it. At length Bulow was strong enough to push down into the valley, and occupy the wood of Pâris, whence he could assail Planchenoit. If he succeeded in this, the French would be defeated in a most ruinous fashion. Hence Napoleon not only sent Lobau's corps to face the Prussians, but himself attended to the new danger. After the repulse of D'Erlon the main action languished, only the cannonade and the fighting before Hougomont continuing, till about four o'clock, when the second main attack began. Forty squadrons of heavy cavalry charged up between Hougomont and La Haye Sainte, against Alten's division, which formed promptly in squares, placed in a double line chess-board fashion, so that the maximum of fire[83] could be poured into the charging horsemen. The guns in front of the English line were necessarily abandoned, but the French could make no impression on the squares, and when in confusion were driven off by cavalry from the English reserves. Again and again the attempt was renewed with the same result, till even the English privates saw how hopeless it was. "Here come these fools again," some of them called out, as a new charge was made. And indeed it is hard to see why they were made: Wellington's line was not broken, or even shaken as yet. Probably the impatience of Ney was to blame, Napoleon being then at a distance engaged with the Prussians. At any rate the net result was the destruction of a great part of the French cavalry, at some cost to Wellington's cavalry, but not much to his infantry, except from the French guns which told with deadly effect on the squares in the intervals of the cavalry charges.