In 1813, Wellington led a new offensive, this time against the French line of communications. He struck through the hills north of Burgos, the Tras os Montes, and switched his supply line from Portugal to Santander on Spain's north coast; this led to the French abandoning Madrid and Burgos. Continuing to outflank the French lines, Wellington caught up with and smashed the army of King Joseph Bonaparte in the Battle of Vitoria, for which he was promoted to field marshal on 21 June. He personally led a column against the French centre, while other columns commanded by Sir Thomas Graham, Rowland Hill and the Earl of Dalhousie looped around the French right and left (this battle became the subject of Beethoven's orchestral piece, the "Wellington's Victory" (Opus 91). The British troops broke ranks to loot the abandoned French wagons instead of pursuing the beaten foe. This gross abandonment of discipline caused an enraged Wellington to write in a famous dispatch to Earl Bathurst, "We have in the service the scum of the earth as common soldiers".