This is a critical study of the key provisions of the law relating to the conduct of combat in armed conflicts on land, illustrated by reference to problems that have arisen during recent conflicts. It is an updated version of the successful first edition but with two additional chapters, dealing with rules relating to the conduct of combat against members of the enemy armed forces and in internal armed conflicts. The approach adopted is to take a proposition of the law of war, examine its historical origins and current exposition, deal with problems of interpretation and application, especially in the light of recent conflicts, and reach conclusions about how it should be applied in practice.