After the Defeat at the Siege of Burgos the allied army lead by Wellington makes a run for it across Spain, giving up their recently won territories in Central Spain to French forces who attempt to encircle and trap Wellington and his fleeing forces. In OTL Wellington and much of the Allied Army manages to escape but what if Wellington is captured or killed? Perhaps if the French pursue him more aggressively or already bad weather was worse or the French realize his retreat earlier on?