Battle of Salamanca. 22^{nd} July 1812] On June 13, the spring rains being over, Wellington, having concentrated his immediate army near Ciudad Rodrigo, marched on Salamanca. His motives for deciding to operate against Marmont rather than in Andalusia seem to have been various, some embracing the whole area of the Peninsula, one at least the practical consideration that his supplies, brought by water up the Douro, could more quickly and easily be conveyed to the army. He had no intention of running serious risks, or of fighting a great battle unless he could do so under favourable conditions. If successful, he could greatly shake the French hold on Spain: if he found Marmont too strong, his retreat into Portugal was insured by possession of the fortresses. Marmont retired at once, leaving garrisons in the forts round Salamanca. These forts offered unexpectedly long resistance, and Wellington, encamped on the high ground north-east of the city, did not think it prudent to risk a battle until they were in his hands, though Marmont's somewhat rash manœuvres, undertaken in the hope of saving them, gave him more than one opportunity. On the 27th the forts fell, and Marmont, having no longer any motive for lingering near Salamanca, and expecting reinforcements from the north, promptly retreated behind the Douro. Wellington followed, but could not pass the river, of which the enemy held or had destroyed the bridges, except by deep and dangerous fords. He could only wait for his antagonist to make the next move, which soon came. On receiving his reinforcements, Marmont re-crossed the Douro, and a series of complicated movements ensued, in which Marmont out-manœuvred Wellington, compelling him to retire on Salamanca again, and seizing passages over the river Tormes above the city. That river, after flowing northwards for some distance, makes a great bend to the westward from a point about east of Salamanca, and then after passing the town, which is on its right bank, flows away north-westwards into the Douro. It was in the space enclosed by this curve of the Tormes, south-east from Salamanca, that the great battle was fought. Marmont's purpose in crossing the river into this space was to threaten the Ciudad Rodrigo road, and so compel Wellington to retreat or lose his one line of communication. Wellington naturally also crossed the Tormes by the fords near Salamanca: being aware that further reinforcements, especially of cavalry, in which Marmont was relatively deficient, would arrive in a day or so, he had made up his mind to retreat at night unless something unexpected should happen. And the unexpected did happen: Marmont, who had hitherto carried off the honours of the campaign so far as manœuvring went, for there had been no important fighting, suddenly committed a gross tactical blunder.