In April 1815, and although the wars had ended with the [Treaty of Ghent]? in December of the previous year, many prisoners of war still remained and some were unfortunate enough to be massacred in the prison at the behest of a drunken British officer.
Dartmoor was reopened thirty years later as a civilian prison and has contained some of Britain's most serious offenders ever since. It has a (misplaced) reputation for being escape-proof.