That province is divided in its whole length by shoots from the Pyrenees, which, with some interruptions, run to the Atlantic shores; for the sierras separating Valencia, Murcia, and Andalusia from the central parts of Spain, are but continuations of those shoots. The Ebro, forcing its way transversely through the ridges, parts Catalonia from Valencia, but the hills, thus broken by the river, push their rocky heads southward to the sea, cutting off Taragona from Tortoza, and enclosing what may be called the eastern region of Catalonia, which contains Rosas, Gerona, Hostalrich, Vich, Barcelona, Manreza, Taragona, Reus, and many more towns. The torrents, the defiles, and other military features of this region have been before described. The western portion of Catalonia lying beyond the principal spine, is bounded partly by Aragon, partly by Valencia; and, like the eastern region, it is an assemblage of small plains and rugged valleys, each, the bed of a river, descending towards the Ebro from the Pyrenees. It contains the fortresses of Balaguer, Lerida, Mequinenza, Cervera, and, near the mouth of the Ebro, Tortoza, which, however, belongs in a military view rather to Valencia than Catalonia. Now the mountain ridge, parting the eastern from the western region of Catalonia, could only be passed by certain routes, for the most part impracticable for artillery, and those practicable, leading upon walled towns at both sides of the defiles. Thus Cervera is situated on the principal and direct line from Lerida to Barcelona; Balaguer, Cardona, and Montserrat, on another and more circuitous road to the same city. Between Lerida and Taragona, stands Momblanch, and between Taragona, and Tortoza, the Fort St. Felippe blocks the Col de Balaguer. All these places were in the hands of the Spaniards, and a number of smaller fortresses, or castles, such as Urgel, Berga, and Solsona, served as rallying points, where the warlike Somatenes, of the higher valleys, took refuge from the moveable columns, and from whence, supplied with arms and ammunition, they sallied, to harass, the flanks and rear, of both the French corps. In the eastern region, the line of operations for the seventh corps, was between the mountains and the sea-coast, and parallel with both; hence, the Spanish irregular forces, holding all the communications, and the high valleys on both sides of the great dividing spine, could at all times descend upon the rear and flanks of the French, while the regular troops, opposed to them on a narrow front, and supported by the fortresses of Gerona, Hostalrich, and Taragona, could advance or retire as circumstances dictated. And upon this principle, the defence of Catalonia was conducted.