It is not clear whether the commanders of the Anglo-Portuguese army thought Loison’s brigade was the advance guard and was an indication that Soult was planning to head east to Spain, but rumours abounded, and Soult later claimed in his Mémoires that he had formed the intention to retreat from Porto into Spain rather than to try to defend the city.120 Wellesley was very conscious that the strategy devised might expose Beresford’s relatively small contingent of between 6,000 and 7,000 (the latter figure probably included his small cavalry detachment) to the full force of Soult’s army, and if a crossing of the Douro did not prove practical, then at least he was to prevent the French coming south over the Douro.121
Beresford was aware that if Soult’s entire force moved east against him, he would not be able to prevent him passing, but with considerable foresight suggested that if Wellesley attacked Porto, and then detached to his right such force as he could spare, the French could be stopped in their retreat and forced to abandon their guns and baggage; in the process probably losing a great number of men.122 Wellesley was adamant that if Soult moved east from Porto with his entire army, Beresford should not attempt to obstruct him for he did not wish ‘to see a single British brigade supported by 6,000–8,000 Portuguese exposed to be attacked by the French army in any but a very good post’.123 Accordingly, Wellesley’s instructions to Beresford were specific. He was not to endanger his force unless he felt strongly he would defeat the enemy:
If the French should weaken their corps about Amaranthe [sic] and Villa Real so as to give you any reason to hope that you can do anything against them, then I wish you to attack them and take any opportunity of getting possession of either of these points. But remember that you are a Commander in Chief of an army & must not be beat & therefore do not undertake anything with your troops if you have not some strong hopes of success.124
Beresford’s force was designated to include the 3rd Brigade under Major General Tilson, but this force of some 1,500 men of the 60th, 87th, 88th and Portuguese grenadiers was delayed amid suggestions that Tilson did not take gladly to being under Beresford’s command.125 Beresford expressed his disappointment to Wellesley at Tilson’s failure to respond to the order to join him with alacrity, more particularly as he failed also to communicate with Beresford on receiving the order.126 Tilson had made it clear he did not wish to serve under Beresford, and in making his report to Wellesley, Beresford castigated Tilson’s performance and made repeated pleas to Wellesley to accede to Tilson’s request.127 Tilson’s wish not to serve under Beresford was clearly not personal but based on the principle of not having to serve under an officer who had been promoted Major General at the same time as himself.128
Following the expedition to clear northern Portugal of the French, Tilson asked to be allowed to resign the command of his brigade and go to England, making the further request that in future he would be employed in the Portuguese army, and therefore under Beresford, but presumably with the step up in rank to Lieutenant General. Wellesley was not prepared to agree to this proposition and Tilson was urged to reconsider his position, being reminded that he must obey the orders of his superior and commanding officer. He gave Tilson leave to resign his command, which Tilson opted to do, though he subsequently sought and obtained leave to withdraw his resignation acknowledging that he had been mistaken regarding his responsibilities.129 Tilson served under Hill at the battle of Talavera later in 1809, but he was to leave the Peninsula the following year, though returning again later in the war.
Wellesley’s successful march on Porto and the surprise crossing of the Douro, causing Soult to flee eastwards on 12 May, is well known. Before setting off from Coimbra with the main army on 7 May, Wellesley started Beresford on his flanking march a day earlier, given the greater distance he had to cover. Beresford reached Viseu on 7 May where he was joined by Wilson and two battalions drawn from Almeida. Beresford proceeded to Lamego on 8 May and the Portuguese regiments of infantry and part of the artillery designated to join the Marshal’s column assembled at Lamego by 9 May, while Tilson’s brigade had reached Viseu.130 Urgent instructions were despatched to Tilson to join Beresford at Lamego by 11 May.131 On 8 May Loison had reached Vila Real and on 10 May he closed up on Mesão Frio. On 10 May, Beresford sent Silveira and a force including the 6th Caçadores over the Douro at Peso da Régua. Loison was engaged and thrown back on Amarante. Beresford followed with his main force, crossing the Douro on 11 May and on approaching Amarante the next day Loison retreated to the far side of the River Tamega to a position of considerable strength.
On 12 May, Wellesley not only captured Porto but put a considerable force under Major General Sir John Murray across the Douro upstream to get behind Soult, who now marched east to join with Loison in the hope of marching to Spain to link up with the French forces there.132 Murray did not seek to stop Soult, perhaps fearing his own force was too small. Soult had expected Loison to stand his ground at Amarante, but instead he retired north west to Guimarães on 13 May, thus leaving Soult’s army in a potential trap between Wellesley and Beresford.133 In difficult conditions Beresford’s army, including Tilson’s brigade which had joined it early that day, crossed the Tamega with the river rising fast because of the rain.134 The crossing took four hours and was led by the 60th, 87th and 88th regiments from Tilson’s brigade, but two companies were unable to cross and a number of men were lost.135
Much of Amarante had been burnt by the retreating French. Soult, realising his danger, destroyed his artillery and abandoning heavy baggage marched to join Loison in Guimarães. Meanwhile, Wellesley was still bringing equipment, including guns and supplies, across the Douro and combined with the exertions of the army this meant he needed a day in Porto before setting off in pursuit of Soult. The latter, with his full force, headed for Braga and Beresford, whose advance guard had come across Soult’s abandoned baggage and destroyed guns on 14 May, when he learnt of the recapture of Porto anticipated that Wellesley would head to Braga. Beresford left a screening force in Amarante and proceeded himself to Chaves by forced march, reaching it late on the evening of 16 May with only part of an exhausted force after three days marching in the rain.136
On the same day, 14 May, he ordered Silveira to Montalegre. The objective was to deny Soult the Montalegre and Chaves exit routes to Spain. While the latter was achieved, the delay in Silveira’s troops reaching Montalegre left open a door for Soult to escape. The French Marshal, now aware that Wellesley was coming up behind him to Braga, ordered Loison in turn to destroy his artillery and the men to abandon anything other than essential food and a reserve of ammunition. With the help of local guides the French army led a desperate but ultimately successful escape to Orense in Spain over the mountains, via Montalegre; Silveira’s force only arriving as the French were leaving on the afternoon of 17 May.137 Though the Portuguese were themselves much wearied, they picked up some French stragglers.
Those of Beresford’s troops who had reached Chaves were exhausted and needed to rest on 17 April while he waited for Tilson’s brigade and that of Bacelar to catch up.138 On 18 May, Beresford did march from Chaves to Monterey, catching up with some of the French near Ginzo, but Soult’s main force by now was far to the east and pursuit was abandoned the following day on Wellesley’s orders, perhaps because of a lack of supplies but also alarming news had reached the latter from MacKenzie that Victor’s corps was on the move into the Tagus valley, having expelled the Loyal Lusitanian Legion from the bridge at Alcantara.139 While Victor had indeed captured the bridgehead at Alcantara, the news that he was advancing into Portugal turned out to be false. Beresford’s exhausted force then returned south to Castelo Branco via Lamego picking up those abandoned on the route north. Beresford himself then proceeded to meet Wellesley at Lamego on 27 May to take stock of the position and coordinate plans for the future.
There was a suggestion in some quarters that Beresford might have driven his forces with greater intensity so as to shut the door on Soult’s escape, but such comment fails to recognise the nature of the extended marches