On the 1st of June the rear was still on the Esla, yet the van entered Zamora, the French retiring on Toro. Next day their rear-guard of cavalry being overtaken by the hussars gave battle, was broken, and driven back on the infantry with a loss of two hundred men. Wellington halted the 3rd to bring the Gallicians down on his left, and to close up his own rear, for he thought the French, who were concentrating, might give battle; but he had entirely mastered the line of the Duero, and those who understand war may say, whether it was an effort worthy of the man and his army. Some of his columns had marched a hundred and fifty, some above two hundred and fifty miles in the wild Tras os Montes, through regions thought to be impracticable even for small corps; forty thousand men, infantry, cavalry, artillery, and even pontoons, all had passed, and been suddenly placed as if by a supernatural power upon the Esla before the enemy knew that they were in movement. The field was now clear for the shock of arms, but the forces were unequally matched. Wellington had ninety thousand men, and more than one hundred pieces of artillery in hand. Twelve thousand were cavalry, the British and Portuguese were seventy thousand; and this mass of regulars was aided by all the Partidas. Sanchez’ horsemen, a thousand strong, were on the right beyond the Duero; Porlier, Barcena, Salazar and Manzo on the left between the Upper Esla and the Carion; Saornil menaced Avila, the Empecinado hovered about Leval; and the Spanish reserve of Andalusia, having crossed the Tagus on the 30th, drew all the numerous small bands swarming around as it advanced. On the other hand, though the French could collect nine or ten thousand horsemen and one hundred guns, their infantry was less than half the number of the allies, being only thirty-five thousand strong, exclusive of Leval. The way to victory was therefore open, and on the 4th Wellington marched forward with a conquering vehemence, pouring a torrent of war, whose depth and violence the king was even now ignorant of. It was thought Joseph would fight on the Carion. But though he had then fifty-five thousand fighting men, exclusive of a Spanish division escorting the convoys and baggage, he did not judge that river a good position and retired behind the upper Pisuerga. Meanwhile he sent Jourdan to examine Burgos castle, and expedited fresh letters, having before written from Valladolid, to Foy, Sarrut and Clausel, calling them towards the plains of Burgos, and others to Suchet, directing him to march upon Zaragoza: but Suchet was then engaged in Catalonia, Clausel was in Aragon, Foy on the coast of Guipuscoa, and Sarrut pursuing Longa in the Montaña.