if for no other reason than the term itself carries too much mythology and revisionist connotations to be worthwhile (by that I mean that it was used by later generations to define and describe an ideal way of conflict that may never have actually existed). Chivalry could also be very class-distinctive and applied to a certain group or limited groups.
That is where I was going. I was thinking about various wars in western history. Beginning somewhere back in the days when chivalry and honor were supposed to be born. For instance, Edward I taking Bruce's wife and daughter, placing them in a cage and hanging them over the wall of his castle. For months if I recall the story correctly. Or the horrific death of Edward II. Or Simon de Montfort and his son being hacked to pieces after surrendering. Or Richard I ordering the massacre of people outside of Acre. Or Henry V cutting off the hands and feet of the resisters.

I could go on. But, if we look at Frontier Warfare, I would say that history points to the subjugation of the native population through very unchivalric acts. The western troops being known to ride into camps and kill everyone and everything. Driving the population before them. we now look askance and question such behaviors based on our modern concept of honor and chivalry, but then these acts were considered proper against a "barbarous" enemy.

Which is reflected in our modern dilemma regarding terrorists or "unlawful combatants" against the Geneva Conventions and Law of Land Warfare. We long ago placed such people outside of the "rules" and treated them as such. Today, we question that practice or its practicality, but only due to the type of war we are waging and our very modern ideas of "civilization". Particularly in a war where "lawfare" weighs heavily against "warfare".

Can you imagine the furor had we summarily executed Khalid Sheihk Mohammed? Even after his participation in 9/11 and various other terrorist acts killing hundreds and thousands? Do we now or in the future ever designate someone outside of these boundaries and protections?

Someone brings up WWII so I think that is another good place to reference, even if it is "total war". It is the question of when we deem whole populations outside of the protections of any code. Was fire bombing Dresden an act of chivalry, honor or necessity? Some would justify it by saying it was part of the strategy to break the will of the people and the ability of the enemy to manufacture the equipment for war. In the end, some say it may have shortened the war and saved tens of thousands of lives, even hundreds of thousands. The same thing we say about Hiroshima or Nagasaki.

We killed millions to save how many?

Does a war for survival make certain acts more acceptable and less considerate of such niceties as chivalry and honor?

Which brings me to the point about Luttrel's unit's decision and the fact that there was a decision to be made at all. If we would kill millions to save hundreds of thousands, if they had killed two to save four, is it only a difference because, paraphrasing Stalin, one is a tragedy and millions a statistic?