I have not got the facts in front of me, but I recall that the Spanish division with Wellington's army was sent back to Spain after only a short time in France, because of their depredations. I think Oman has something on that.

Portuguese and Spanish soldiers who mistreated French civilians -- or any civilians for that matter -- would be punished under their own military law. I am not sure how strict the Spanish were in punishing plunderers, etc., and I cannot say I blame them, if they were not, and that may have been another reason why Wellington sent them away.

Portuguese military discipline appears to have been much stricter as witnessed by Jorge Quinte-Nova's post below.

By 1813-1814, British military discipline was very strict and with the inception of the Detachment General Court Martial, which provided for very swift and severe punishment of offenders, there were much fewer cases of mistreatement of French civilians on the part of the British army. Wellington himself testified before the 1836 parliamentary inquiry on military punishments that, by the time his army got over the border, he had it well in hand and the number of offences had diminished markedly, in contrast to his problems in 1809-1812.

dg