The main difficulties of the Army of the North arose from geographical facts. While the plains of Leon and Old Castile could be scoured by cavalry, and easily traversed by flying columns, so that it was not impossible to keep some sort of order in them, this flat upland was bordered on the north by the long chain of the Cantabrian sierras and their foot-hills, broad, rugged, and nearly roadless. Behind these again lay the narrow and difficult coast-land of Asturias and Santander, cut up into countless petty valleys each drained by its own small river, and parted from its neighbours by spurs of the great sierras. How was this mountain region, seventy miles broad and two hundred long, to be dealt with? The French had no permanent garrisons on the coast between Gijon, the port of Oviedo, which was generally occupied by a detachment of Bonnet’s division, and Santander, not far from the borders of Biscay[266]. This last Bessières describes as ‘a bad post from every point of view, only to be defended by covering it with large bodies of troops,’ and only accessible by a series of difficult defiles. In the Cantabrian highlands dwelt Longa and Porlier, with bands which had assumed the proportions of small armies; they could communicate with the sea at any one of a dozen petty ports, and draw arms and supplies from the British cruisers of the Bay of Biscay. Even Mina would occasionally get in touch with the sea through this coast-land, though his main sphere of operations was in Navarre. There were dozens of smaller bands, each based on its own valley, but capable of joining its neighbours for a sudden stroke. Again and again French columns worked up into these sierras from the plain of the Douro, and went on a hunt after the patriots. Sometimes they caught them and inflicted severe loss; more often they were eluded by their enemies, who fled by paths that regular troops could not follow, into some distant corner of the mountains. It was impossible to garrison each upland valley with a force that could resist a general levy of the insurgents. Even little towns like Potes, in the Liebana, Longa’s usual head quarters, which were repeatedly taken, could not be kept. The ‘Army of the North’ would have required 150,000 men instead of the 70,000 whom Bessières actually commanded, if it was to master the whole of this difficult region. Indeed, Cantabria could only have been conquered by an enemy possessing a sea force to attack it in the rear, and occupy all its little ports, as well as an overwhelming land army operating from all sides. To the end of the war Longa and Porlier, often hunted but never destroyed, maintained themselves without any great difficulty in their fastnesses. Nothing but the general despair and demoralization that might have followed the extinction of the patriotic cause in the whole of the rest of Spain, could have brought the war in this region to an end. Nothing of the kind occurred: the