At about two o’clock in the afternoon on the 15th the British commander-in-chief made up his mind that he must delay no longer, and ordered his army to march to its right, in the two lines in which it was already arranged. The mass of cavalry in front of Aldea Tejada remained stationary, to cover the movement of the infantry behind its rear: the smaller body of horse on the left held its ground about the Arapiles, till all the divisions had passed on, and then followed as a rearguard. The entire army marched in fighting trim: if attacked at any moment it had only to front to its left flank, and then would be in order of battle. The movement had to be slow for the first few miles, since neither the front nor the rear column was on a good track until it reached the river Zurgain, and there fell into one of the three parallel roads which run from Salamanca to Ciudad Rodrigo. Moreover the rain, which had been a mere drizzle in the morning, turned to a heavy torrential downpour just as the army was starting. The country paths became quagmires in a few minutes; and when the usually insignificant Zurgain came in sight it was already a roaring river, only to be forded with care. The march was toilsome in the extreme, and the troops, who had expected and desired a general action, were sodden and sulky. ‘I never saw the men in such a bad humour,’ observes one intelligent eye-witness[181]. The march was absolutely unmolested by the French, and the columns, having crossed the Zurgain, fell into the three parallel roads which run side by side for many miles from Salamanca--the southern one to Matilla, the central one to Maza de San Pedro and San Muñoz, the northern one (the so-called Calzada de Don Diego) to Aldehuela de la Boveda[182]. Of these the second is the regular high road from Salamanca to the frontier, the other two secondary lines of communication. They are extraordinarily convenient for the retreat of an army which must be kept together, the distance between the two side-roads and the central one being seldom over five miles, and often no more than three. The only misfortune was that the train of transport had gone off, by Colonel Gordon’s error[183], on an entirely different and divergent route, towards Rollan and San Felices. The army, after falling into the designated roads, pursued its way till after dark and bivouacked in the patches of forest on the farther side of the Valmusa river, about 10 miles from Salamanca. The head-quarters were at the village of Carnero on the central road[184]. The night was miserable, no food was distributed, and though wood was abundant it was hard to light fires, owing to the incessant rain. The troops were tired and footsore, and straggling had once more begun.