Geoffroi de Charny (c. 1300 – 19 September 1356) was a French knight and author of at least three works on chivalry. One of his works, Questions for the Joust, Tournaments and War consists of a series of open-ended questions regarding the law of tournaments and the proper conduct of war. The complete set of questions has been translated into English and made available online.
Of the three sets of questions, the questions concerning war tend to be more philosophical and give a fascinating insight into the moral and strategic issues that were important to medieval knights. For example:
W 6: A captain and lord of a country meets another one of the same sort in war; and they come to the point of combat. Which will be better: that the captain goes before his banner and his banner after him, or that the banner should be in front and the captain behind?
W 7: Two captains as described above fight each other. One is defeated but remains on the field so long that he sees and understands that he is unable to recover his fortunes or the day; and the battle has been very well fought. Which is the better thing for him to do: remain and take his chances, or leave so that he can recoup? And if he leaves, should he thereby lose his honor?
W 25: In so far as there are two types of war, and the one kind should be fought differently than the other, as some say. One kind is guerre guerriable, which takes place as a dispute from one frontier to another in disdain of one lord for another, and which often is able to move from one frontier to another in a variety of ways. The other kind of war is the desire to conquer a country, which one claims as lord but another lord holds. And this kind of war of conquest ought not to be waged. Some say war is more suitable in the manner of guerre guerriable. And so I ask how a war of conquest ought to be conducted.
W 30: There is a battle as above in which many men at arms of the defeated party depart and go away. Some consider that these have gone on their honor without being defeated; and many others consider that those who have gone are defeated. How can this be?
W 31: A captain of men at arms rides out in the field and orders some of his scouts to see the situation of his enemies who are in the field; and these scouts are among the more capable of his people. And at the approach of their enemies one party of their enemies pursues them as fast as they can go; and the scouts retreat from their enemies and are able to retreat without loss. So there are some of the scouts who turn back and meet their enemies, and perform arms like good people should; and others retreat to their captain and make their report. Which of these are to be more valued and praised: those who went back to their lord or those who are praised?