In lieu of an abstract, here is a brief excerpt of the content:

Correspondence Combat Data and the 3:l Rule To The Editors: 1 T*N.Dupuy I have some observations regarding John J. Mearsheimer’s article, “Assessing the Conventional Balance: The 3:l Rule and its Critics,” in the Spring 1989issue of International Security.’ The ostensible purpose of Mearsheimer’s article was to reply to an article by Joshua Epstein in the Spring 1988issue of International Security.* In fact Mearsheimer devoted a substantial proportion of his article to direct and indirect attacks on me, my writings and my data bases, and he devoted all 10 pages of an appendix to “correcting”my data. Space limitations preclude a complete response, so I shall focus my comments upon the most important of Mearsheimer’s errors. Mearsheimer’s indirect attacks on me relate to what he calls ”the wellknown and widely accepted 3:l rule of thumb” (Mearsheimer, p. 54). The direct attacks challenge the accuracy and reliability of data in several of my publications. The 3:l Rule of Thumb Mearsheimer inaccuratelyimplies that I am a critic of the 3:lrule. In Chapter 4 of my recent book, Understanding War:History and Theory of Combat, entitled ”TheThree-to-One Theory of Combat,” I point out that the 3:l rule is a crude rule of thumb that suggests that in a military battle the attacker is likely to be successful if he has an overall numerical strength superiority of three-toone over the defender. I show that this very general strength relationship between attacker and defender is sometimes used by military planners of Colonel T.N. Dupuy, USA, Ref., is President of Data Memory Systems, lnc. He commanded American, British, and Chinese troops in combat in Burma, 194345; he has been a military planner with the War Department General Staff,Army General Staff, and SHAPE staff; and is the author of several works on combat theory. 1. John J. Mearsheimer, ”Assessing the Conventional Balance: The 3:l Rule and Its Critics,” International Security, Vol. 13, No. 4 (Spring 1989),pp. 54-89. 2. Joshua M. Epstein, “Dynamic Analysis and the Conventional Balancein Europe,” lnternational Security, Vol. 12, No. 4 (Spring 1988), pp. 154-165. Znternationnl Security, Summer 1989 (Voi. 14, No. 1) 0 1989 by the President and Fellows of Harvard College and of the Massachusetts Institute of Technology. 195 lnternational Security 14:l I 196 both sides for pre-battle assessment of the likelihood of victory or defeat. The basis for the rule of thumb is that in historical instances an attacker with such an advantage has usually been successful. Sincein most battles attackers rarely have had such a one-sided strength preponderance, the opposing commanders or planners can use this rule of thumb to assess options open to the attacker to try to enhance his strength sufficiently at least to approximate a 3:l superiority, or to the defender to assure that the attacker is unable to bring such a preponderance to bear. Despite its crudeness, the so-called rule can be a useful first step in the planning process for either side. I also show that the rule is so crude that it is practically useless as an analytical tool. In his article Mearsheimer refers to my book. He ignores the relevant chapter. On the basis of my experiences as a combat commander and as a highlevel staff planner, I can say that my view of the 3:l rule is consistent with the views of modern military practitioners, at least in the United States and NATO armies. If I am right in what I said in my book, and say here, then almost everything that Mearsheimer says about the 3:l rule of thumb in his article is wrong. For example, Mearsheimer asserts that the 3:l rule applies only to what he calls “breakthroughbattles.” I know of no authority for such a statement, and he cites no source. The other principal problem with Mearsheimer’s personal version of the 3:l rule is that he says that it does not apply to mere numerical strength ratios; rather he asserts the need to adjust the numerical ratio to arrive at a ”combatpower” ratio that reflects such factors as quality...

pdf

Share