The second chain is much more important, and more strongly[p. 78] marked: it divides Old from New Castile, the valley of the Douro from that of the Tagus. In its central and western parts it is really a double range, with two narrow valleys between its chief ridges. These valleys are drained by the Zezere and Alagon, two tributaries of the Tagus which flow parallel for many scores of miles to the broad river which they feed. If we call this great system of mountains the chain of New Castile it is only for convenience’ sake: the Spaniards and Portuguese have no common name for them. In the east they are styled the Sierra de Ayllon; above Madrid they are known as the Guadarrama—a name sometimes extended to the whole chain. When they become double, west of Madrid, the northern chain is the Sierra de Gata, the southern the Sierra de Gredos. Finally in Portugal the extension of the Sierra de Gata is called the Sierra da Estrella, the southern parallel ridge the Sierra do Moradal. The whole system forms a very broad, desolate, and lofty belt of hills between the Tagus and Douro, through which the practicable passes are few and difficult. Those requiring notice are (1) the Somosierra Pass, through which runs the great northern road from Burgos to Madrid: its name is well remembered owing to the extraordinary way in which Napoleon succeeded in forcing it (against all the ordinary rules of war) in the winter of 1808. (2) There is a group of three passes, all within twelve miles of each other, across the Guadarrama, through which there debouch on to Madrid the main roads from North-western Spain—those from (a) Valladolid and Segovia, (b) from Astorga, Tordesillas, and Arevalo, (c) from Salamanca by Avila. After this group of passes there is a long space of impracticable hills, till we come to the chief road from north to south, parallel to the Portuguese frontier: it comes down the valley of the Alagon from Salamanca, by Ba?os and Plasencia, on to the great Roman bridge of Alcantara, the main passage over the Middle Tagus. This is a bad road through a desolate country, but the exigencies of war caused it to be used continually by the French and English armies, whenever they had to transfer themselves from the valley of the Douro to that of the Tagus. Occasionally they employed a still worse route, a little further west, from Ciudad Rodrigo by Perales to Alcantara. When we get within the Portuguese frontier, we find a road parallel to the last, from Almeida by Guarda to Abrantes, also a difficult route, but like it in perpetual use: usually, when the French marched from Salamanca[p. 79] to Alcantara, Wellington moved in a corresponding way from near Almeida to Abrantes. This road runs along the basin of the Zezere, though not down in the trough of the river, but high up the hillsides above it. Spanish and Portuguese roads, as we shall see, generally avoid the river banks and run along the slopes far above them.
The next great chain across the Peninsula is that which […]