In medieval times, confrontations were sometimes settled by David vs. Goliath single combat. The mercenary condottori were bribed to abandon their employers. We had Free Fire Zones where any individual seen â man, woman or child â could be shot on sight. The Americans had a policy they called MGR; the Mere Gook Rule where no consideration was given as to friend, foe or neutral to any indigent person just because they were deemed Gooks. Shoot 'em all, Let God sort it out. Shock and Awe. Hiroshima. All these were harsh realities of war. Leaving aside any modern day consideration of right or wrong, which of these â or any other part of past custom and practice of war â would most effectively be reintroduced in the areas where we are in conflict?