Meantime a furious artillery duel raged between the opposing ridges. Wellington had ordered his gunners not to fire at the French batteries, but only at the French columns, while the French, in the main, concentrated their fire on the British guns. French practice under these conditions was naturally very beautiful, for no hostile bullets disturbed their aim, and the British gunners fell fast; yet their fire on the French masses was most deadly. At two o'clock Napoleon launched his great infantry attack, led by D'Erlon, against La Haye Sainte and the British left. It was an attack of terrific strength. Four divisions, numbering 16,000 men, moved forward in echelon, with intervals between them of 400 paces; seventy-two guns swept as with a besom of fire the path along which these huge masses advanced with shouts to the attack, while thirty light guns moved in the intervals between them; and a cavalry division, consisting of lancers and cuirassiers, rode on their flank ready to charge the broken masses of the British infantry. The British line at this point consisted of Picton's division, formed of the shattered remains of Kempt's and Pack's brigades, who had suffered heavily at Quatre Bras. They formed a mere thread of scarlet, a slender two-deep line of about 3000 men. As the great mass of the enemy came slowly on, the British line was "dressed," the men ceased to talk, except in monosyllables, the skirmishers lying flat on the trampled corn prepared to fire. The grape of the French guns smote Picton's red lines with fury, and the men fell fast, yet they closed up at the word of command with the most perfect coolness. The French skirmishers, too, running forward with great speed and daring, drove in the British skirmishers, who came running back to the main line smoke-begrimed and breathless. As the French masses began to ascend the British slope, the French guns had to cease their fire for fear of striking their own forces. The British infantry, too, being drawn slightly back from the crest, were out of sight, and the leading French files saw nothing before them but a cluster of British batteries and a this line of quickly retreating skirmishers. A Dutch-Belgian brigade had, somehow, been placed on the exterior slope of the hill, and when D'Erlon's huge battalions came on, almost shaking the earth with their steady tread, the Dutch-Belgians simply took to their heels and ran. They swept, a crowd of fugitives, through the intervals of the British lines, and were received with groans and hootings, the men with difficulty being restrained from firing upon them.