The latter, indeed, was not to have moved till the king joined him but, believing that his own army was ample for the purpose; and eager to gain a victory, unhampered by the king's presence, he suddenly crossed at Tordesillas, and it was only by his masterly movements, and a sharp fight at Castile, that Wellington succeeded in concentrating his army on the Aqueda. The British general drew up his army in order of battle, on the heights of Vallesa; but the position was a strong one, Marmont knew the country perfectly and, instead of advancing to the attack, he started at daybreak on the 20th, marched rapidly up the river, and crossed it before any opposition could be offered, and then marched for the Tormes. By this movement he had turned Wellington's right flank, was as near Salamanca as were the British, and had it in his power, unless checked, to place himself on the road between Salamanca and Ciudad, and so to cut their line of retreat. Seeing his position thus turned, Wellington made a corresponding movement, and the two armies marched along lines of hills parallel with each other, the guns on both sides occasionally firing. All day long they were but a short distance apart and, at any moment, the battle might have been brought on. But Wellington had no opportunity for fighting, except at a disadvantage; and Marmont, having gained the object for which he had manoeuvred, was well content to maintain his advantage. At nightfall the British were on the heights of Cabeca and Aldea Rubia, and so secured their former position at San Christoval. Marmont, however, had reached a point that gave him the command of the ford at Huerta; and had it in his power to cross the Tormes when he pleased, and either to recross at Salamanca, or to cut the road to Ciudad. He had proved, too, that his army could outmarch the British for, although they had already made a march of some distance, when the race began, he had gained ground throughout the day, in spite of the efforts of the British to keep abreast of him. Moreover, Marmont now had his junction with the king's army, approaching from Madrid, securely established; and could either wait for his arrival, or give battle if he saw a favourable opportunity. Wellington's position was grave. He had not only to consider his adversary's force, but the whole course of the war, which a disaster would imperil. He had the safety of the whole Peninsula to consider, and a defeat would not only entail the loss of the advantage he had gained in Spain, but would probably decide the fate of Portugal, also. He determined, however, to cover Salamanca till the last moment, in hopes that Marmont might make some error that would afford him an opportunity of dealing a heavy blow.