To kill someone for committing murder is a punishment incomparably worse than the crime itself. Murder by legal sentence is immeasurably more terrible than murder by brigands.
Capital punishment kills immediately, whereas lifetime imprisonment does so slowly. Which executioner is more humane? The one who kills you in a few minutes, or the one who wrests your life from you in the course of many years?
If soldiers are punished before they have grown attached to you, they will not prove submissive; and, unless submissive, then will be practically useless. If, when the soldiers have become attached to you, punishments are not enforced, they will still be unless.