Marmont, who had fortified posts at Zamora and Toro, and had broken the bridges at those places and at Puente Duero and Tudela, preserving only that of Tordesillas, now took a position on the right of the Duero. His left was at Simancas on the Pisuerga, which was unfordable, and the bridges at that place and Valladolid, were commanded by fortified posts. His centre was at Tordesillas, and very numerous, and his right was on some heights opposite to Pollos. Wellington indeed caused the third division to seize the ford at the last place which gave him a command of the river, because there was a plain between it and the enemy’s heights, but the ford itself was difficult and insufficient for passing the whole army. Head-quarters were therefore fixed at Rueda, and the forces were disposed in a compact form, the head placed in opposition to the ford of Pollos and the bridge of Tordesillas, the rear occupying Medina del Campo and other points on the Zapardiel and Trabancos rivers, ready to oppose the enemy if he should break out from the Valladolid side. Marmont’s line of defence, measured from Valladolid to Zamora, was sixty miles; from Simancas to Toro above thirty, but the actual line of occupation was not above twelve; the bend of the river gave him the chord, the allies the arc, and the fords were few and difficult. The advantage was therefore on the side of the enemy, but to understand the true position of the contending generals it is necessary to know the secondary coincident operations. While the armies were in presence at Salamanca, Silveira had filed up the Duero, to the Esla river, menacing the French communications with Benavente. D’Urban’s horsemen had passed the Duero below Zamora on the 25th and cut off all intercourse between the French army and that place; but when Marmont fell back from Aldea Rubia, D’Urban recrossed the Duero at Fresno de la Ribera to avoid being crushed, yet immediately afterwards advanced beyond Toro to Castromonte, behind the right wing of the enemy’s new position. It was part of Wellington’s plan, that Castaños, after establishing the siege of Astorga, should come down by Benavente with the remainder of his army, and place himself in communication with Silveira. This operation, without disarranging the siege of Astorga, would have placed twelve or fifteen thousand men, infantry, cavalry, and artillery, behind the Esla, and with secure lines of retreat; consequently able to check all the enemy’s foraging parties, and reduce him to live upon his fixed magazines, which were scanty. The usual Spanish procrastination defeated this plan.