Long commanded a brigade (consisting of a single regiment - the 13th Light Dragoons) at the Battle of Vitoria in 1813. He fought at the Battle of the Pyrenees later in the same year. When Marshal Soult's large-scale attack across the Pyrenees was launched, on 25 July 1813, it caught Wellington's forces off guard and in an extended state. Long's brigade was acting as the vital link between the two main bodies of Anglo-allied troops. It was in this situation that Long performed the most important service in his active military career. General Lowry Cole sent a dispatch to Wellington to say that a French army of about 35,000 men had forced him from his defensive position and that he was falling back. The dispatch came into Long's hands and he, upon his own initiative, opened it and made a copy to be sent to his immediate superior Sir Rowland Hill. Hill then forwarded the dispatch to Wellington who had recently moved his headquarters. The original copy of the dispatch went to the location Wellington's previous headquarters and did not reach him that evening. Long's intelligent actions allowed Wellington time to react to Soult's movements; had any appreciable delay occurred before Wellington became apprised of the situation the results could have been disastrous for the allied army.