It is a custom in England that the victors in battle kill nobody

In the Wars of the Roses casualties were limited precisely because they were civil wars. On both sides the commanders were anxious to win popular support, not lose it by indulging in bloody massacres. Thus one contemporary observer of the wars, the shrewd French politician Philippe de Commynes noted that ‘it is a custom in England that the victors in battle kill nobody, especially none of the ordinary soldiers, because everyone wants to please them.

J. Gillingham, The wars of the Roses (1981), 12