Soon after the assault on Badajoz, Wellesley (now raised to the peerage as Marquess Wellington) marched into northern Spain. For a month the British and French armies marched and counter-marched against each other around Salamanca. On 22 July, Wellington took advantage of a momentary French dispersion and gained a complete victory at the Battle of Salamanca. After occupying Madrid, Wellington unsuccessfully besieged Burgos. In October, the army retreated to Portugal. This "Winter Retreat" bore similarities to the earlier retreat to Corunna, as it suffered from poor supplies, bitter weather and rearguard action.