While the armies were in presence some fighting had taken place at Burgos, Dubreton had again obtained possession of the ruins of the church of San Roman and was driven away next morning; and now in pursuance of Wellington’s determination to retreat, mines of destruction were formed in the horn-work by the besiegers, and the guns and stores were removed from the batteries to the parc at Villa Toro. But the greatest part of the draught animals had been sent to Reynosa, to meet the powder and artillery coming from Santander, and hence, the eighteen-pounders could not be carried off, nor, from some error, were the mines of destruction exploded. The rest of the stores and the howitzers were put in march by the road of Villaton and Frandovinez for Celada del Camino. Thus the siege was raised, after five assaults, several sallies and thirty-three days of investment, during which the besiegers lost more than two thousand men and the besieged six hundred in killed or wounded; the latter had also suffered severely, from continual labour, want of water, and bad weather, for the fortress was too small to afford shelter for the garrison and the greater part bivouacked between the lines of defence. RETREAT FROM BURGOS. [Sidenote: See Plan 5.] This operation was commenced on the night of the 21st by a measure of great nicety and boldness, for the road, divaricating at Gamonal, led by Villatoro to the bridge of Villaton on the one hand, and the bridge of Burgos on the other, and Wellington chose the latter, which was the shortest, though it passed the Arlanzan river close under the guns of the castle. The army quitted the position after dark without being observed, and having the artillery-wheels muffled with straw, defiled over the bridge of Burgos with such silence and celerity, that Dubreton, watchful and suspicious as he was, knew nothing of their march until the Partidas, failing in nerve, commenced galloping; then he poured a destructive fire down, but soon lost the range. By this delicate operation the infantry gained Cellada del Camino and Hormillas that night, but the light cavalry halted at Estepar and the bridge of Villa Baniel. Souham, who did not discover the retreat until late in the evening of the 22d, was therefore fain to follow, and by a forced march, to overtake the allies, whereas, if Wellington to avoid the fire of the castle had gone by Villaton, and Frandovinez, the French might have forestalled him at Cellada del Camino.