The mists were now rapidly clearing up, and in a short time the whole French army could be seen advancing. They moved towards the British left, and Wellington ordered the troops at once to retire. The British fell back in three columns, and marched for the Guarena, through Torrecilla de la Orden. The French also marched straight for the river, and now one of the most singular sights ever presented in warfare was to be seen.

The hostile armies were marching abreast, the columns being but a few hundred yards apart, the officers on either side waving their hands to each other. For ten miles the armies thus pressed forward the officers urging the men, and these straining every nerve to get first to the river. From time to time the artillery of either side, finding a convenient elevation, would pour a few volleys of grape into the opposing columns, but the position of the two armies, did not often admit of this. Gradually Cotton's men, fresher than the French, who had, in the two previous days, marched fifty miles, gained ground, and, reaching the river, marched across by the ford, the winners of the great race by so little that one division, which halted for a moment to drink, was swept by forty pieces of French artillery, which arrived on the spot almost simultaneously with it.

On the Guarena the British found the remaining divisions of the army, which had been brought up from Canizal. These checked Marmont in an attempt to cross at Vallesa, while the 29th and 40th Regiments, with a desperate bayonet charge, drove Carier's French division back as it attempted to push forward beyond Castrillo. Thus the two armies faced each other on the Guarena, and Marmont had gained absolutely nothing by his false movement at Toro, and his long and skillful detour by Tordesillas.

Quickly the rest of the day passed, as did the one which followed, the troops on both sides resting after their fatigues. Wellington expected to be attacked on the next morning and his army was arranged in two lines ready for the combat. At daybreak, however, Marmont moved his army up the river, crossed at a ford there, and marched straight for Salamanca, thus turning Wellington's right, and threatening his communications. The British at once fell back, and the scene of the previous day was repeated the armies marching along the crest of two parallel hills within musket shot distance of each other.

This time however, the French troops, although they had marched considerably farther than the English proved themselves the best marchers, and when night fell Wellington had the mortification of seeing them in possession of the ford of Huerta on the Tormes, thus securing for Marmont the junction with an army which was approaching under King Joseph, and also the option of either fighting or refusing battle. Wellington felt his position seriously threatened, and sent off a despatch to the Spanish General Castanos, stating his inability to hold his ground, and the probability that he should be obliged to fall back upon Portugal. This letter proved the cause of the victory of Salamanca for it was intercepted by the French, and Marmont, fearing that Wellington would escape him, prepared at once to throw himself upon the road to Ciudad Rodrigo, and thus cut the British line of retreat, in spite of the positive order which he had received from King Joseph not to fight until he himself arrived with his army.

Upon the 21st both armies crossed the Tormes, the French at Alba and Huerta, the British at Aldea Lengua, and San Marta. Upon that day the news reached Wellington that General Chauvel, with 2000 cavalry, and 20 guns, would reach Marmont on the evening of the 22d, or the morning of the 23d, and the English general therefore resolved to retreat, unless Marmont should, by some mistake, give him a chance of fighting to advantage.

Close to the British right, and the French left, were two steep and rugged hills, called the Hermanitos, or Brothers, and soon after daybreak on the 22d, the French seized upon the one nearest to them, while the British took possession of the other. Then, watching each other, the two armies remained until noon, for Wellington could not commence his retreat by daylight; but a long cloud of dust along the road to Ciudad Rodrigo showed that the baggage of the army was already en route for Portugal. Marmont now determined to make a bold stroke to cut off Wellington's retreat, and, although all his troops had not yet arrived, he ordered Maucune, with two divisions, to march round by the left and menace the Ciudad road. It was at three o'clock in the afternoon, and Wellington, who had been up all night, thinking that Marmont would make no move that day, had gone to lie down for an hour or two, when Tom Scudamore who, from an elevated point, was watching the movements of the enemy, hurried in with the news that the French were pushing their left round towards the Ciudad Road.

Wellington leaped to his feet, and hurried to the high ground, where he beheld, with stern satisfaction, that Marmont, in his eagerness to prevent the British escape, had committed the flagrant error of detaching his wing from his main body. Instantly he issued orders for an attack, and the great mass of men upon the British Hermanito moved down upon the plain to attack Maucune in flank, while the third division was ordered to throw itself across his line of march, and to attack him in front. As the advance across the plain would be taken in flank by the fire from the French Hermanito, General Pack was ordered to assail that position directly the British line had passed it.

Marmont, standing on the French Hermanito, was thunder-struck at beholding the plain suddenly covered with enemies, and a tremendous fire was at once opened upon the advancing British. Officer after officer was despatched to hurry up the French troops still upon the march, and when Marmont saw the third division dash across Maucune's path, he was upon the point of hurrying himself to the spot, when a shell burst close to him, and he was dashed to the earth with a broken arm, and two deep wounds in his side.

Thus, at the critical point of the battle, the French army was left without a head.