This monograph is the ninth offering in the Combat Studies Institute's (CSI) Global War On Terrorism (GWOT) Occasional Papers series. The author, a retired Army lieutenant colonel and CSI historian, has produced a study that examines the evolution and continued applicability of the corpus that constitutes the law of war. As background, he provides a theoretical framework and the development of the law within Western and, specifically, U.S. Army doctrine and regulation. He then presents a case study of the British suppression of the Mau Mau insurgency between 1952 and 1960 in Kenya, a conflict with particular resonance today. Some of the more relevant characteristics of the conflict include the clash between Western and non-Western cultures and an initially asymmetric fight between conventional security forces and loosely organized, poorly equipped insurgents. It makes no claim that every lesson learned by the British during that counterinsurgency operation can be directly applied by the United States to the challenges of the GWOT, but this analysis does offer some insight about applying the law of war to an unfamiliar, non-Western environment. The genesis of this study is the public discourse asserting the possibility that the GWOT may require new rules and new law-of-war prescripts. This important discussion is fraught with complexities and long-term implications; the moral force in warfare is incredibly significant and any changes to the legal framework in place must be very carefully considered. Do we follow the law of war to the letter, do we remain consistent with the principles of Geneva, or do we approach the conflict as a new challenge requiring fundamental revisions to the law? According to the author, law-of-war violations are neither necessary nor excusable for successful prosecution of military operations in any environment, and because the law of war in its current form is more than adequate to face the new GWOT challenges, it does not warrant revision.