One problem is that you characterize a whole society from the worst behaviour of an army facing desertion, lack of supply, fruitless stand in a baren country.
The other his your partial lecture of events : the greatest crimes of british in the Peninsula were Ciudad Rodrigo, Badajoz, San Sebastian. Were senior officers tried and punished for the misbehaviour of their men, how many men were hanged when thousands were guilty ?
Please don't answer with the right to sack an assaulted city : spanish cities were supposed to be british allies, and it's the same level of excuse as the french arguing about "right of fighting armed civilians".
This his no defence of french crime in the Peninsula : they exist, are much more numerous than the english one; but no nation, even the most "civilised" ones, was immune of this behaviour in war.
Sincerely,
Jean.