Yet Wellington was not insensible of the critical nature of his position, and longed for night or Bluecher. It was now seven, and the Prussians had been expected at three. In less than an hour, the sound of artillery was heard in the expected direction, and a staff officer brought word that the head of the Prussian column was at Planchenoit, nearly in the rear of the French reserve. Bonaparte, when told of their advance, maintained that it was Grouchy's long-expected force coming up; but when he saw them issue from the wood, and perceived the Prussian colors, he turned pale, but uttered not a word. Napoleon's Imperial Guards--his veteran troops--were now advancing, covered by a tempest of shot and shells, toward the ridge behind which lay the British infantry to gain a shelter from the fire. Wellington eagerly watched the dense cloud as it approached; and when it arrived within a hundred yards, advancing on horseback to the brow of the ridge, he exclaimed, "Up, Guards, and at them!" In a moment the men were on their feet--the French closed on them, when a tremendous volley drove the whole mass back; but the old Imperial Guard recovered, yet only to receive a second volley as deadly as the first, followed by a bold charge with the bayonet, which forced them down the slope, and up the opposite bank. In vain the French attempted to support them by taking the Guards in flank. Lord Hill brought forward the extreme right of the army, in the form of a crescent, which overlapping the horsemen, they were crushed as in a serpent's folds, while the infantry fell back, re-formed, and occupied their former place on the ridge. Wellington's quick eye already detected the confusion caused by the Prussian attack under General Buelow on the French rear. Hastily closing his telescope, he exclaimed, "The hour is come! Now every man must advance!" Forming into one long line, four men deep, the whole infantry advanced, with a loud cheer, the sun at the instant streaming out as if to shed his last glories on the conquerors of that dreadful day. Headed by the duke, with his hat in hand, the line advanced with spirit and rapidity, while the horse-artillery opened a fire of canister-shot on the confused masses. For a few minutes they stood their ground gallantly; and, even when the allied cavalry charged full upon them, four battalions of the Old Guard formed squares, and checked its advance. As the grapeshot tore through the ranks of the veterans, they closed up again, and, to every summons to surrender, gave the stern reply, "The Guard never surrender--they die!"