To understand this process, it is necessary to consider factors absent in the topography of the Gaulish plains, and especially the factor of that unconquerable tangle of mountains which occupies all the north-western triangle of the Peninsula.

The ocean boundaries of the Iberian quadrilateral are nearly square to the points of the compass. It is not so with the internal divisions that mark off its central part. Here the edges of the high and arid plateaux, the deep trenches of the rivers, the mountain ranges, the boundaries of the plains at their feet, run slantways from north-east to the south-west. This slant determined the boundaries of Mohammedan expansion, while the Asiatics and Africans still retained the energy to advance; it determined the successive frontiers of the Reconquest, as our race slowly ousted the invader and reached at last the sea-coast of Granada. The Arab and the Moor were masters of Narbonne and all the Roussillon on the east, when, on the west, they could not cross the mouth of the Mulio a hundred miles to the south. They were at Jaca within a day’s march of the watershed along the Roman Road, when, to the immediate west of it, they could not hold Fuente; they could not even reach Pamplona, though that western town is two marches at least from the main crest. Toledo was reconquered a generation before Saragossa, though Saragossa is by nearly two degrees more northerly, because Toledo was west of Saragossa. The last Mohammedan kingdom was crowded, after the thirteenth century, into the extreme south-east, as the surviving remnant of the free Europeans of the Peninsula had been crowded into the extreme north-west in the eighth.

If the boundaries of undisputed Mohammedan rule be traced for various dates, the receding wave will be found in general to follow curves that lead, like the main features of the land, from the north-east downwards towards the Atlantic.

This main character in the geography and history of Spain, the south-westerly trend of the mountain ridges, largely determined the fortunes of those fighting bands of mountaineers who ceaselessly pressed southward until they had wholly driven out the invader and reconstituted the unity of Europe. It determined the first advance to be, not from the Pyrenees, but from the Asturias, and the first captain connected with the Christian resistance after the overwhelming of all that civilization, Pelayo (from whose blood Leon, Castille, Aragon, and Navarre descend) had his stronghold, not in the Pyrenees, but a week’s march to the west, along the Biscayan coast at Cangas. Within the decade of the invasion he had checked the invader in his own hills at Covadonga.

All the eighth century is full of that successful spirit in the north-west—but nowhere else. Alfonso, the husband of Pelayo’s daughter, struck the note with his boast, “No pact with the infidel,” and the tradition or prophecy that Christendom would regain the south, springs from him. He conquered down to the Douro, over what is to-day the mountain frontier of Portugal; he began those long cavalry raids into the heart of Moorish land. He rode into Astorga, into Zamora, into Segovia itself—within sight of the central range of the Guadarama: riding back with booty, harassed and harassing, nowhere permanently fixing himself save in the towns of the west, upon the Lower Douro, but building on the ridges of his defence, those block-houses, the “Castille” from which, long after, the frontier province began to take its name.

All the ninth century that spirit grew. The body of St. James was found under the Star at Compostella—its shrine became the national sacrament as it were, a perpetual refreshment for arms, and a symbol, in its wild isolation among the rocks of Galicia, of the impregnable places from which the Reconquista drew its ardour. The advance continued. The frontier counties consolidated and were named.

Leon was permanently held, Burgos was founded. If one takes for a date the opening years of the tenth century, just after Alfred had saved England also from the pagan, and just after the Counts of Paris had saved northern Gaul, there is a full Spanish kingdom standing up against the Mohammedan power, a king has been crowned in Leon and has died in peace at Zamora. The cavalry raids have pushed—once at least—to Toledo. All the north-west lay permanently Christian beyond a line that ran from the corner of Gaul to the Douro and down the Douro to the sea; and this united triangle of Roman land formed a base from which the pushing back of the alien could proceed.

How did this disposition of forces affect the Pyrenees? Let it first be noted that the newly organized Christian country lay wholly to the west of the range. In the Pyrenees themselves the Mohammedan flood had washed every valley. The crest had been traversed and retraversed; both slopes were for a moment held by the invaders. Abd-ur-Rahman had sent or led his thousands by the Roman roads of Roncesvalles and Urdos and over the Ostondo and the lower passes of the west. The mule tracks of these rocks had been twice crowded with the white cloaks of the Arabs. In the east, Narbonne was held for fifty years, and with it all the Catalans. Even in the high centre of the chain, where there is no passing between the Somport and the Cerdagne, wherever there was something to rob or to destroy, the invaders had penetrated. There was not here, as in the Asturias, untouched land.

When the crest of the wave retreated, when the Mohammedan came back defeated from Gaul, the high valleys attained—it may be guessed—a savage independence.