This essay recommends criteria for determining the effectiveness of war in attaining the objectives of national policy. While I draw on the writings of Sun Tzu, Carl von Clausewitz, and B.H. Liddell Hart, my conclusions are not necessarily theirs, although I do not believe they are inconsistent. A few words at the outset about what this paper does not do. Sun Tzu's statement that "to subdue the enemy without fighting is the acme of skill" (The Art of War, p. 77) is perhaps the earliest theoretical underpinning for deterrence strategies. I subscribe to this view of the ultimate purpose of armed forces. However, both because, realistically, wars must be fought in order to give a nation's warfighting capabilities the credibility needed for deterrence, and because the topic of this essay explicitly deals with the act of war rather than its avoidance, I do not deal with the effectiveness of deterrence beyond this brief comment. Neither do I concern myself with what national policy objectives are or should be. While this has presented some intellectual problems -- I firmly believe that the correctness or morality of specific national objectives cannot be separated from the appropriateness of military action -- I have tried to frame my arguments at a general level. Thus, I am not prescribing criteria for determining the effectiveness of war in achieving what I think should be United States national security objectives in the 199Os (although that is a tempting subject), but rather trying, in Clausewitzian fashion, to draw up some general principles which can be used to judge the usefulness of war within the context of any country's national security objectives.