Such was the posture of affairs when Beresford who had quitted the northern army after the combat of Foz d’Aronce, arrived at Portalegre with twenty thousand infantry, two thousand cavalry, and eighteen guns.
His instructions were to relieve Campo Mayor, and to besiege Olivenza and Badajos. The first had already surrendered, but the marshal, being within two marches of it, judged that he might surprise the besieging corps, and, with this view, put his troops in motion the 23d. In the morning of the 25th his advanced guard of cavalry, supported by a detachment of infantry, under colonel Colborne, came suddenly upon Campo Mayor, just as Latour Maubourg was marching out in confusion, with twelve hundred cavalry, three battalions of infantry, some horse-artillery and the battering train of thirteen guns. The allies pursued him, and passing over a wooded rise of ground, issued forth at the other side by some gentle slopes on either flank of the French, who were in a fine plain. Colonel Colborne was on the right and at a considerable distance from the enemy, but colonel Head, with the thirteenth light dragoons, was on the left, close to them, and supported by colonel Otway with two squadrons of the seventh Portuguese. The heavy cavalry was in reserve; and while in this state the French hussars, suddenly charging with a loose rein from behind their infantry, fell some on the Portuguese and some on the thirteenth dragoons. So fiercely did these last on both sides come together, that many men were dismounted by the shock, and both parties pierced clear through to the opposite side, then re-formed, and passed again in the same fearful manner to their own ground: but Head’s troopers rallied quicker than the French, and riding a third time closely in upon them, overthrew horse and man, receiving at the same time the fire of the infantry squares. Nevertheless, without flinching, they galloped upon the battering train, hewed down the gunners, and, drawing up beyond the French line of march, barred the way, in expectation that the heavy cavalry would also fall on; but Beresford would not suffer the latter to charge, and the French infantry returned for their guns and resumed their march. The thirteenth and the Portuguese, however, continued the pursuit, in a rash and disorderly manner, even to the bridge of Badajos, and being repulsed by the guns of that fortress, were followed by Mortier in person, and lost some prisoners. Of the allies one hundred men were killed or hurt, and above seventy taken. Of the enemy about three hundred suffered, one howitzer was captured, and the French colonel Chamorin was slain in single combat by a trooper of the thirteenth.
To profit from sudden opportunities, a general must be constantly with his advanced guard in an offensive movement. When this combat commenced, Beresford was with the main body, and baron Trip, a staff-officer, deceived by appearances, informed him, that the thirteenth had been cut off. Hence the marshal, anxious to save his cavalry, which he knew could not be reinforced, would not follow up the first blow, truly observing that the loss of one regiment was enough. But the regiment was not lost, and, the country being open and plain, the enemy’s force and the exact posture of affairs were easy to be discerned. The thirteenth were reprimanded, perhaps justly, for having pursued so eagerly without orders, yet the unsparing admiration of the whole army consoled them.
Campo Mayor was thus recovered so suddenly, that the French left eight hundred rations of bread in the magazines; and they also evacuated Albuquerque and Valencia d’Alcantara, being infinitely dismayed by the appearance of so powerful an army in the south: indeed, so secretly and promptly had lord Wellington assembled it, that its existence was only known to the French general by the blow at Campo Mayor. But, to profit from such able dispositions, it was necessary to be as rapid in execution, giving the enemy no time to recover from his first surprise; and this was the more essential, because the breach in Badajos was not closed, nor the trenches obliterated, nor the exhausted magazines and stores replenished. Soult had carried away six battalions and a regiment of cavalry, four hundred men were thrown into Olivenza, three thousand into Badajos; thus, with the losses sustained during the operations, Mortier’s numbers were reduced to less than ten thousand men: he could not therefore have maintained the line of the Guadiana and collected provisions also, and Beresford should have instantly marched upon Merida, driven back the fifth corps, and opened a fresh communication by Jerumenha with Elvas; the fall of Badajos would then have been inevitable. The confusion occasioned by the sudden appearance of the army at Campo Mayor and the charge of the thirteenth dragoons guaranteed the success of this march; the English general might even have passed the river at Merida before Mortier could have ascertained his object.
Beresford, neglecting this happy opportunity, put his troops into quarters round Elvas, induced thereto by the fatigue and wants of the soldiers; especially those of the fourth division, who had been marching incessantly since the 6th of the month, and were bare-footed and exhausted.
He had been instructed, by lord Wellington, to throw a bridge over the Guadiana at Jerumenha; to push back the fifth corps; and to invest Olivenza and Badajos. The Portuguese government had undertaken not only to provide the means for these operations, but had actually reported that they were collected at Elvas and Jerumenha; that is to say, that provisions, shoes, battering guns, ammunition, and transport were there; that the Guadiana abounded in serviceable craft; that twenty large boats, formerly belonging to Cuesta, which had been brought away from Badajos before the siege, were at Elvas; and that all other necessaries would be sent from Lisbon. It now appeared that no magazines of provisions or stores had been formed; that very little transport was provided; that only five of Cuesta’s boats had been brought from Badajos; that there was no serviceable craft on the river, and that some small pontoons, sent from Lisbon, were unfit to bear the force of the current, or to sustain the passage of guns. The country, also, was so deficient in provisions, that the garrison-stores of Elvas were taken to feed the army.
All these circumstances combined to point out Merida as the true line of operations; moreover, plenty of food was to be had on the left bank of the Guadiana, and the measures necessary to remedy the evil state of affairs on the right bank, did not require the presence of an army to protect them. The great distress of the fourth division for shoes, alone offered any serious obstacle; but, under the circumstances, it would not have been too much to expect a momentary effort from such an excellent division, or, it might without danger even have been left behind.
Marshal Beresford preferred halting until he could procure the means of passing at Jerumenha; an error which may be considered as the first and principal cause of those long and bloody operations which afterwards detained lord Wellington nearly two years on the frontiers of Portugal. For, during Beresford’s delay, general Phillipon, one of the ablest governors that ever defended a fortress, levelled the trenches, restored the glacis, and stopped the breach; meanwhile Latour Maubourg, who had succeeded Mortier in command of the troops, covered the country with foraging parties and filled the magazines.
Captain Squires, of the engineers, now undertook to bridge the Guadiana under Jerumenha, by fixing trestle-piers on each side in the shallows, and connecting them with the five Spanish boats; wherefore, a squadron of cavalry was secretly passed over, by a ford, to protect the workmen from surprise. The 3d of April, the bridge being finished, the troops assembled during the night in the woods near Jerumenha, being to cross at daylight; but the river suddenly swelling, swept away the trestles, rendered the ford impassable, and stopped the operations. No more materials could be immediately procured, and the Spanish boats were converted into flying bridges for the cavalry and artillery, while Squires constructed a slight narrow bridge for infantry with the pontoons and with casks taken from the neighbouring villages. To cover this operation a battalion was added to the squadron already on the left bank, and the army commenced passing the 5th of April; but it was late in the night of the 6th, ere the whole had crossed and taken up their position, which was on a strong range of hills, covered by a swampy rivulet.