In the following campaigns the king took possession of the kingdom of Cordova, of all the passes of Sierra Morena on the side of Estremadura, and finally of Jaen (1246) which was ceded after a siege of more than a year by its lord, Muhammed al-Akhmar, who in the first place was king of Arjona, of which he was a native, and afterwards of Granada when he acknowledged himself the vassal of Ferdinand. This enterprise being so successfully terminated, Ferdinand resolved to employ the great military resources now at his disposal in the conquest of the town and kingdom of Seville, the richest and most powerful of the remaining Mussulman possessions, but almost entirely dependent on its own strength. The Christians were well aware that Seville could expect but little assistance from Africa, and therefore undertook the enterprise with celerity. Immediately on the fall of Jaen, Ferdinand set out for Seville with his whole army, accompanied by the king of Granada and his troops, as vassal of Castile. He laid waste to the territory of Carmona, and took possession of Alcalá de Guadaira, which he made into his arsenal; he also commanded the country surrounding the capital and Xeres to be devastated. The following year (1247) commenced the celebrated siege of Seville, in which a fleet, which had been constructed in Santander and Biscay, took part commanded by the admiral Boniface, penetrating by San Lucar on the Guadalquivir. The Moors could receive provisions and relief solely from Nieblo and Algarve by means of a bridge of boats uniting the fortress with Triana. This was destroyed by the admiral, who got ready two of the strongest ships of his fleet and awaited a violent sea wind, when, with all the sails of both ships set, he weighed anchor at the moment the full tide was strongest, and let the ships be hurled against the bridge of boats, which was broken by the force of the shock, thus well-nigh destroying the only hope of the besieged. From that day a scarcity of food was experienced in the thickly populated town, but the stores laid in were sufficiently abundant to enable the town to hold out for another six months. [Sidenote: [1247-1252 A.D.]]