Terence had engaged several peasants to watch the roads leading from Oporto, and as soon as he learned that a long train of baggage and heavy guns was leaving the city by the road to Amarante, he crossed the valley, took up a position on the Catalena hill flanking the road, and as the waggons came along opened a sudden and heavy fire upon them. Although protected by a strong guard the convoy fell into confusion, many of the horses being killed by the first volley. Some of the drivers leapt from their seats and deserted their charges, others flogged their horses, and tried to push through the struggling mass. An incessant fire was kept up, but just as Terence was about to order the whole corps to charge down and complete the work, a large body of cavalry, followed by a heavy body of infantry, appeared on the scene. This was Merle's division, that had hastened up from Valonga on hearing the firing. The advance of the cavalry was checked by the musketry fire, but Merle at once ordered his infantry to mount the hill and drive the Portuguese off. The latter stood their ground gallantly for some time, inflicting heavy loss upon their assailants. Terence saw, however, that he could not hope to withstand long the attack of a whole French division, and leaving two companies behind to check the enemy's advance, he marched along the crest of the hill until he came upon the road crossing from Amarante to the Ave river. By this time he had been joined by the rear-guard, who had retired in time to make their escape before the French reached the top of the hill. Merle posted a brigade along the crest of the ridge to prevent a repetition of the attack, and to cover Soult's line of retreat, if he were forced to fall back; while Terence took up his position near Pombeiro, whence he presently saw the convoy enter Amarante. He had the satisfaction, however, of noticing that it was greatly diminished in length, a great many of the waggons having been left behind owing to the number of horses that had been killed. His attack had had another advantage of which he was unaware, for it had so occupied Merle's attention that he had neglected to have all the boats taken across the river, which enabled Murray's command to cross the next day, an error which, had Murray been possessed of any dash and energy, would have proved fatal to the French army.