Marmont was now joined by Bonnet's army from Asturias, and thus once more recovered a decided superiority in numbers. Wellington accordingly retired in his turn; and for some days the two hostile armies moved in parallel lines, often within half cannon shot, each waiting for some mistake of which advantage might be taken. The weather was all the while intensely hot; numbers fainted on the march; and when any rivulet was in view, it was difficult to keep the men in their ranks. On the evening of the 21st of July, Wellington and Marmont lay in full view of each other, on two opposite rising grounds near Salamanca; a great storm of thunder and rain came on, and during the whole night the sky was bright with lightning. Wellington was at table when he received intelligence that his adversary was extending his left,--with the purpose of coming between him and Ciudad Rodrigo. He rose in haste, exclaiming, "Marmont's good genius has forsaken him," and was instantly on horseback. The great battle of Salamanca was fought on the 22nd of July. The French were attacked on the point which Marmont's movement leftwards had weakened, and sustained a signal defeat. The commander-in-chief himself lost an arm: 7000 prisoners, eleven guns, and two eagles were taken; and it was only the coming on of night that saved the army from utter destruction. Wellington pursued the flying enemy as far as Valladolid, and then, re-crossing the Douro, marched upon Madrid. King Joseph fled once more at his approach, and the English were received with enthusiasm in the capital of Spain.