The 20th of July proved to be a most interesting day of manœuvring, but still brought no decisive results. Early in the morning the whole French army was seen in march, with its head pointing southward, continuing the movement that it had begun on the previous day. Marmont had made up his mind to proceed with the hitherto unsuccessful scheme for turning his adversary’s right wing[494], in the hope of either cutting him off from his communication with Salamanca, or of catching him with his army strung out on too long a line from continuous and rapid movement. The character of this day’s march differed from that of the 19th, because the single well-marked Guarena valley ceased after a time to separate the two hostile armies. That little river is formed by three tributaries which meet at and above the village of El Olmo: each of them is a paltry brook, and their courses lie along trifling irregularities of the broad tableland from which they descend. It is only after their junction that they flow in a deep well-marked valley, and form a real military obstacle. Of the three brooks, that which keeps the name of Guarena lies most to the east: up its right bank and towards its source Marmont’s march was directed. Wellington’s parallel movement southward, on the other hand, was directed along the left bank of the Poreda, the middle brook of the three. Between them there was at first a narrow triangular plateau, on which neither party trespassed save with cavalry scouts.
After a few miles of marching Marmont ordered his advanced guard to cross the Guarena, which they could do with ease, no British being near, save a few cavalry vedettes. He then turned the head of his column south-westward, instead of keeping to his original direction due south. Having crossed the Guarena he came in sight of the British column marching on the other side of the Poreda brook from Vallesa. The movements of the two armies tended to converge, the point on which both were moving being the village of Cantalpino. It seemed likely that the heads of the marching columns must collide, and that a combat, if not a general action, would ensue. Each army was marching in an order that could be converted into a battle line by simply facing the men to right or to left respectively. Wellington had his troops in three parallel columns, the first one, that nearest to the French, being composed of the 1st, 4th, 5th, and Light Divisions, the second, which would have formed the supporting line if the army had fronted and gone into action, contained the 6th and 7th and Pack’s and Bradford’s brigades: the 3rd Division and España’s Spaniards formed a reserve, moving farthest from the enemy. The light cavalry were marching ahead of the column, the heavy cavalry and D’Urban’s Portuguese brought up their rear. Marmont was clearly seen to be moving in a similar formation, of two columns each composed of four infantry divisions, with Curto’s chasseurs ahead, and Boyer’s dragoons at the tail of the line of march[495].
The day was warm but clouded, so that the sun did not shine with full July strength, or the long march which both armies carried out would have been brought to an end by exhaustion at a much earlier hour than was actually the case. As the long morning wore on, the two hostile forces gradually grew closer to each other, owing to the new westward turn which Marmont had given to his van. At last they were within long artillery range; but for some time no shot was fired, neither party being willing to take the responsibility of attacking an enemy in perfect order and well closed up for battle. Either general could have brought on a fight, by simply fronting to flank, in ten minutes; but neither did so. Marmont remarks in his Mémoires that in his long military service he never, before or after, saw such a magnificent spectacle as this parallel march of two bodies of over 40,000 men each, at such close quarters. Both sides kept the most admirable order, no gaps occurred in either line, nor was the country one that offered advantage to either: it was very nearly flat, and the depression of the Poreda brook became at last so slight and invisible that it was crossed without being noticed. The ground, however, on which the French were moving was a little higher than that on which the allies marched[496].
The converging lines of advance at last almost touched each other at the village of Cantalpino: the light cavalry and the 1st Division, at the head of Wellington’s front (or eastern) column of march had just passed through it, when Marmont halted several batteries on a roll of the ground a few hundred yards off, and began to shell the leading battalions of the 4th Division, which was following closely behind the 1st. Wellington ordered Cole not to halt and reply, nor to attack, but to avoid the village and the French fire by a slight westerly turn, to which the other divisions conformed, both those in the first and those in the second line[497]. This amounted to the refusing of battle, and many officers wondered that the challenge of Marmont had been refused: for the army was in perfect order for fighting, and in excellent spirits. But Wellington was taking no risks that day.
The slight swerve from the direct southerly direction at Cantalpino made by the allied army, distinctly helped Marmont’s plan for turning its right, since by drawing back from its original line of movement it allowed the enemy to push still farther westward than his original line of march had indicated. This meant that he was gradually getting south of Wellington’s vanguard, and would, if not checked, ultimately arrive at the Tormes river, near the fords of Huerta, from which he would have been edged off, if both armies had continued in their original direction. During the early afternoon the parallel move continued, with a little skirmishing between cavalry vedettes, and an occasional outbreak of artillery fire, but no further developments. The baggage in the English rear began to trail behind somewhat, owing to the long continuance of the forced marching, and D’Urban’s Portuguese, who shepherded the stragglers, had great difficulty in keeping them on the move. A few score sick and foot-sore men, and some exhausted sumpter-beasts, fell behind altogether, and were abandoned to the French[498].
Late in the afternoon the armies fell further apart, and all save the outlying vedettes lost sight of each other. This was due to the fact that Wellington had made up his mind to settle down for the night on the heights of Cabeza Vellosa and Aldea Rubia, where Marmont had taken up his position a month before, when he retired from before San Cristobal. This was good fighting-ground, on which it was improbable that the French would dare to deliver an attack. The 6th Division and Alten’s cavalry brigade were detached to the rear, and occupied Aldea Lengua and its fords.
This had been a most fatiguing day—the British army had marched, practically in battle formation, not less than four Spanish leagues, the French, by an extraordinary effort, more than five. When the camp-fires were lighted up at night, it was seen that the leading divisions of the enemy were as far south as Babila Fuente, quite close to the Tormes and the fords of Huerta: the main body lay about Villaruela, opposite the British bivouacs at Aldea Rubia and Cabeza Vellosa. An untoward incident terminated an unsatisfactory day: D’Urban’s Portuguese horse coming in very late from their duty of covering the baggage-train, were mistaken for prowling French cavalry by the 3rd Division, and shelled by its battery, with some little loss of men and horses. The mistake was caused by a certain similarity in their uniform to that of French dragoons—the tall helmets with crests being worn by no other allied troops[499].
The net result of the long parallel march of July 20th was that Marmont had practically turned Wellington’s extreme right, and was in a position to cross the Upper Tormes, if he should choose, in prolongation of his previous movement. The allied army was still covering Salamanca, and could do so for one day more, if the marching continued: but after that limit of time it would be forced either to fight or to abandon Salamanca, the main trophy of its earlier campaign. There remained the chance of falling upon Marmont’s rear, when his army should be occupied in crossing the Tormes, and forcing him to fight with his forces divided by the river. If this offensive move were not taken, and the parallel march were allowed to continue, the next day would see the armies both across the Tormes, in the position where Graham and Marmont had demonstrated against each other on June 24th. Wellington could not, however, begin his southward move till he was certain that the enemy was about to continue his manœuvre on the same plan as that of the last two days. If he started too early, Marmont might attack the San Cristobal position when it was only held by a rearguard, and capture Salamanca. Till an appreciable fraction of the French were seen passing the Tormes it was necessary to wait.
It appeared to Wellington that his adversary’s most probable move would be the passage of the Tormes by the fords at and just above Huerta. That he would abandon his previous tactics, and attack the British army, was inconsistent with the caution that he had hitherto displayed. That he would continue his march southward, and cross the river higher up, was unlikely; for the obvious passage in this direction, by the bridge of Alba de Tormes, was commanded by the castle of that town, which had been for some time occupied by a battalion detached from Carlos de España’s division. Wellington looked upon this route as completely barred to the French: he was unaware that the Spanish general had withdrawn his detachment without orders on the preceding afternoon. This astonishing move of his subordinate was made all the worse by the fact that he never informed his chief that he had taken upon himself to remove the battalion. Indeed Wellington only heard of its disappearance on the 23rd, when it was too late to remedy the fault. He acted on the 21st and 22nd as if Alba de Tormes were securely held. It would appear that Carlos de España thought the castle too weak to be held by a small force, and moved his men, in order to secure them from being cut off from the main army, as they clearly might be when the French had reached Babila Fuente. But the importance of his misplaced act was not to emerge till after the battle of Salamanca had been fought.
At dawn on the 21st Wellington withdrew his whole army on to the San Cristobal position[500], and waited for further developments, having the fords of Aldea Lengua and Santa Marta conveniently close if Marmont should be seen crossing the Tormes. This indeed was the move to which the Marshal committed himself. Having discovered at an early hour that Alba de Tormes was empty, and that there was no allied force observing the river bank below it, he began to cross in two columns, one at the fords of Huerta, the other three miles higher up-stream at the ford of La Encina. Lest Wellington should sally out upon his rear, when the greater part of his army had got beyond the Tormes, he left a covering force of two divisions in position between Babila Fuente and Huerta. This, as the day wore on, he finally reduced to one division[501] and some artillery. As long as this detachment remained opposite him, Wellington could not be sure that the French might not attack him on both sides of the Tormes.