Moore, before retreating, received intelligence of Soult's 16,000-man corps' scattered and isolated position at Carrión and that the French were unaware of the British army's position. On 15 December, he seized this opportunity to advance on the French near Madrid, hoping that to defeat Soult and possibly divert Napoleon's forces. A junction with Baird on 20 December, advancing from Corunna, raised Moore's strength to 23,500 infantry, 2,400 cavalry and 60 guns and he opened his attack with a successful raid by Lieutenant-General Paget's cavalry on the French picquets at Sahagún on 21 December. However, Moore failed to follow up against a surprised Soult. Moore halted for two days and allowed Soult to concentrate his corps.