On the 11th of December the march began, and for the next ten days the army advanced farther and farther into the country. So far Moore had only Soult's army opposing his advance towards Burgos, and it might be possible to strike a heavy blow at that general before Napoleon, who was convinced that the British must fall back into Portugal if they had not already begun to do so, should come up. He had been solemnly assured that he should be joined by Romana with 14,000 picked men, but that general had with him but 5,000 peasants, who were in such a miserable condition that when the British reached the spot where the junction was to be effected, he was ashamed to show them, and marched away into Leon. The British, in order to obtain forage, were obliged to move along several lines of route. Sir David Baird's division joined them as they advanced, and when they reached the Carrion their effective force amounted to 23,583 men, with sixty pieces of artillery. On the French side, Soult had--on hearing of the British advance to the north-east, by which, if successful, they would cut the French lines of communication between Madrid and the frontier--called up all his detached troops, and wrote to the governor of Burgos to divert to his assistance all troops coming along the road from France, whatever their destination might be. On the 21st Lord Paget, with the 10th and 15th Hussars, surprised a French cavalry force at Sahagun, and ordered the 15th to turn their position and endeavour to cut them off. When with the 10th Hussars Lord Paget arrived in the rear of the village, he found six hundred French dragoons drawn up and ready to attack him. He at once charged and broke them and pursued them for some distance. Twenty were killed, thirteen officers and 154 men taken prisoners. On the 23d, Soult had concentrated his forces at the town of Carrion, and that night the British troops were got in motion to attack them, the two forces being about even in numbers; but scarcely had he moved forward when reports, both from Romana and his own spies, reached Sir John Moore to the effect that his march had achieved the object with which it was undertaken. Orders had been sent by Napoleon for the whole of the French armies to move at once against the British, while he himself, with the troops at Madrid, 70,000 strong, had started by forced marches to fall upon him. The instant Moore received this information he arrested the forward movement of his troops. His object had been attained. The French invasion of the south was arrested, and time given to the Spaniards. There was nothing now but to fall back with all speed. It was well indeed that he did not carry out his intention of attacking Soult. The latter had that day received orders from the emperor not to give battle, but to fall back, and so tempt Moore to pursue, in which case his line of retreat would have been intercepted and his army irretrievably lost.