Despite what some posts and your quote suggest, the previous thread on POW camps shows that not all prisoners were kept in hulks. So a variation in treatment. As you say, comparisons and overall strategy is what's needed.
OT personal anecdote - at the outbreak of WW II my father was interned as an enemy alien in a boarding house at Douglas on the Isle of Man. After the powers that be had decided that he and others could enlist, they were trucked to a mainland city to do so. On their return, waiting for their release, they enjoyed the unusual status of enemy aliens who were members of the British army. Since they had no training, some fellow internees, German students who had been German army officers, drilled the group in basic training. My father always regards this as typically English - a combination of pragmatism and eccentricity.
Wonder if things had changed much since Wellington's day?