Busaco is an instructive battle in more ways than one. From Wellington's side it is an instance of a political battle, as Napier calls it, of political motives, not military ones, determining a general's action. On Massena's side it illustrates the important lesson that faulty information may easily be ruinous. Not only had he taken the wrong route, believing it to be the best; he also engaged under the impression that the only other alternative was a retreat nearly to Almeida, whereas all the time there was a road over the mountains to his right, which would have enabled him to turn Busaco. On the night of the battle he found this out, and masking the movement next day with a skirmishing attack on the position, he threw his whole army into this narrow cross-road. Had the English general been less hampered by the political conditions, he might well have made Massena rue his audacity in trying so proverbially dangerous a thing as a flank march in presence of the enemy. As it was he felt bound simply to resume his retreat, of which, once in the open country, there could be no cessation, until the lines of Torres Vedras were reached. Massena had never even heard of the lines till a short time before he came in sight of them; it is strange that so little was known about them, seeing that no such elaborate works had been constructed in Europe since the days when the Romans, in the decline of the empire, built their great walls in Northumberland and elsewhere to keep out the barbarians. Massena reconnoitred them from end to end, in the hope of finding a weak spot; but the more he looked at them, the more hopeless the prospect of an assault appeared, for every day in fact added to their strength. After a month he withdrew to Santarem, high up the Tagus, where subsistence was procurable, and there remained all the winter. Wellington was far too severely hampered by politics to attack him. The Portuguese nation was as a whole sound in its patriotism, and the troops only wanted to be taught; but the politicians were selfish, narrow-minded and factious to an incredible extent, and Wellington found it harder to master the politicians than to stop Massena. Moreover the English government was all this time in a state of perplexity and weakness,[70] and gave the army in Portugal nothing which could on any pretence be withheld.