Leaving the barren basin of the Guadiana to proceed southward, we find across our path a range of first-rate importance, the southern boundary of the central plateaux of Spain: dropping down from its crest we are no longer among high uplands, but in the broad low-lying semi-tropical plain of Andalusia, the richest region of Spain. The chain between the fertile valley of the Guadalquivir and the barren plateau of La Mancha is known for the greater part of its course as the Sierra Morena, but in its western section it takes the name of Sierra de Constantino. The passes across it require special notice: the most eastern and the most important is that of Despeña Perros, through which passes the high road from Madrid to Cordova, Seville, and Cadiz. At its southern exit was fought the fight of Baylen, in which the armies of Napoleon received their first great check by the surrender of Dupont and his 20,000 men on July 23, 1808. Higher up the defile lies another historic spot, on which Christian and Moor fought the decisive battle for the mastery of Spain in the early years of the thirteenth century, the well-known fight of Las Navas de Tolosa. The Despeña Perros has two side-passes close to its left and right: the former is that of San Estevan del Puerto: the latter is known as the ‘King’s Gate’ (Puerto del Rey). All these three defiles present tremendous difficulties to an assailant from the north, yet all were carried in a single rush by the armies of Soult and Sebastiani in 1810. The central pass of the Sierra Morena lies ninety miles to the left, and is of much less importance, as it starts from the most arid corner of La Mancha, and does not connect itself with any of the great roads from the north. It leads down on to Cordova from Hinojosa. Again sixty miles to the west three more passes come down on to Seville, the one by Llerena, the second by Monasterio, the third by Fregenal: they lead to Badajoz and Merida. These are easier routes through a less rugged country: they were habitually used by Soult in 1811 and 1812, when, from his Andalusian base at Seville, he used to go north to besiege or to relieve the all-important fortress of Badajoz. Last of all the great Spanish chains is that which lies close along the Mediterranean Sea, forming the southern edge of the fertile Andalusian plain. It is the Sierra Nevada, which, though neither the longest nor the broadest of the ranges of the south, contains the loftiest peaks in Spain, Mulhaçen and La Veleta. This chain runs from behind Gibraltar along the shore, till it joins the mountains of Murcia, leaving only a very narrow coast-strip between its foot and the southern sea. Three roads cut it in its western half, which, starting from Granada, Ronda, and Antequera all come down to the shore at, or in the neighbourhood of, the great port of Malaga. The parts of the coast-line that are far from that city are only accessible by following difficult roads that run close to the water’s edge.