Trevor N. Dupuy’s Combat Attrition Verities

Operating room setup, 3d Surgical Hospital (Mobile Army), Fort George G. Meade, MD. Office of Medical History, U.S. Army Medical Department
Office of Medical History, U.S. Army Medical Department

Trevor N. Dupuy developed some hypotheses about casualty rates in combat in the process of quantifying the effects of surprise and relative combat effectiveness.[1] After testing these hypotheses against historical combat data, Col. Dupuy believed them valid enough to be considered verities. His confidence in them ranged from absolute for most to reasonable certainty for a few. The first two points are statements of combat experience, but they are directly relevant to the nature of battle attrition. As with his verities of combat, these will be discussed in more detail in subsequent posts.

Personnel Attrition Verities

  1. In the average battle, the attack’s numerical strength is about double the defender’s.
  2. In the average modern battle the attacker is more often successful than the defender.
  3. Casualty rates of winners are lower than those of losers.
  4. Small forces casualty rates are higher than those of large forces.
  5. More effective forces inflict casualties at a higher rate than less effective opponents.
  6. There is no direct relationship between force ratios and casualty rates.
  7. In most modern battles, the numerical losses of attacker and defender are often similar.
  8. Casualty rates for defenders vary inversely with strength of fortifications.
  9. Casualty rates of a surprising force are lower than those of a surprised force.
  10. In the average modern battle, attacker casualty rates are somewhat lower than defender casualty rates.
  11. In bad weather, casualty rates for both sides decline markedly.
  12. In difficult terrain, casualty rates for both sides decline markedly.
  13. The casualty-inflicting capability of a force declines after each successive day in combat.
  14. Casualty rates are lower at night than in daytime.
  15. Casualty rates are higher in summer than in winter.
  16. The faster the front line moves, the lower the casualty rates for both sides.
  17. Casualty rates seem to decline during river crossings.
  18. An “all-out” effort by one side raises loss rates for both sides.
  19. A force with greater overall combat power inflicts casualties at a greater rate than the opponent.
  20. The killed-to-wounded distribution of personnel casualties in twentieth century warfare is consistent.
  21. Average World War II division engagement casualty rates in Western Europe were 1% to 3% per day.
  22. Attrition rates in the 1973 October War were comparable to World War II.
  23. Casualty rates for major power forces in minor hostilities after 1945 are about half those experienced in World War II.

Material Attrition Verities

  1. Material loss rates are related to personnel casualty rates.
  2. Tank loss rates are five to seven times higher than personnel casualty rates.
  3. Attacker tank loss rates are generally higher than defender tank loss rates.
  4. Artillery material loss rates are generally about one-tenth personnel casualty rates.
  5. Self-propelled artillery loss rates are two-to-three times greater than for towed guns.
  6. The loss rates of light, to medium, to heavy artillery weapons are in the proportion: 2.2/1.8/1.0.


[1] Trevor N. Dupuy, Attrition: Forecasting Battle Casualties and Equipment Losses in Modern War (Falls Church, VA: NOVA Publications, 1995), pp. 98-103. A slightly different version of this list was originally published in Trevor N. Dupuy, Understanding War: History and Theory of Combat (New York: Paragon House, 1987), pp. 174–180.

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Shawn Woodford
Shawn Woodford

Shawn Robert Woodford, Ph.D., is a military historian with nearly two decades of research, writing, and analytical experience on operations, strategy, and national security policy. His work has focused on special operations, unconventional and paramilitary warfare, counterinsurgency, counterterrorism, naval history, quantitative historical analysis, nineteenth and twentieth century military history, and the history of nuclear weapon development. He has a strong research interest in the relationship between politics and strategy in warfare and the epistemology of wargaming and combat modeling.

All views expressed here are his and do not reflect those of any other private or public organization or entity.

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One comment

  1. I do not necessarily disagree with the verities but I think some of them require modifications.
    There is a general misconception about Force Ratios (Quantity wise), pure Combat Casualties and Attrition Warfare.
    I’ll try to quote (and translate) Napoleon’s tactics here “When badly outnumbered he managed, by swift maneuvering, to throw the mass of his army against portion of the enemy’s, thus being stronger at the decisive point.”
    Yamashita did the same in Singapore. A larger army has a higher “coordinative difficulty and investment”.
    Of course the term “general” must be taken into account as not all Battles are comparable to Cannae.

    “4.Small forces casualty rates are higher than those of large forces.”
    This is rather complicated, these units could be exposed to more fire and/or seen more combat, I would argue that it is very case sensitive (being outgunned/Firepower per capita vs conducting difficult Operations, Market Garden/Cassino/Warsaw Uprising etc.).
    Consequently, this obscures some evaluations (actually many) about utilizing Mass and overall size comparisons.

    “3. Casualty rates of winners are lower than those of losers.”
    Certainly not for the Soviets.

    I remember Dr.Zetterlings post on some verities:

    Attrition, suppression, modifying the enemy’s behavior and the ability to conduct manuever warfare are all interrelated. The suppressive (and behavoir modification) effects of weapons are related (maybe not linearally related) to their lethality, probability of use and protective measures against them, however imperfectly that may be preceived.

    There is no “school of attrition warfare”. This appears to be a creation of the “school of manuever warfare”, so they have someone to argue against. I am not sure what the “school of manuever warfare” is claiming that is not already incorporated and part of US Army Doctrine, however imperfectly that may be executed.

    In the end, attrition is always important. It is the fear of being attrited that causes commander’s to modify their behavior and that suppresses troops. While wars are not initially won by attrition, any war that lasts longer than 6 months (I am tempted to say 6 weeks) becomes a war of attrition. If the enemy’s political targets (capital, border areas, resources) are not taken, or their will to resist is not broken, then what you have is a war of attrition with manuever now being a means to that end (attrition). At that point, maneuver’s primary object is to place force at an advantage so as to acheive superior attrition and we are back to JFC Fuller’s eight principals of warfare (Manuever, Mass, Suprise, etc.).

    If I recall correctly, he stated that Attrition is not something an Assailant or Defender forces on the enemy, rather than an “antithetical result” of certain combat factors.
    Example: Tactical and technological superiority opposed by vast territory and a larger capacity to wage war (resulting in an operational stalemate but not necessarily a tactical or in maneuver, still increasing Attrition).
    Actually, the Battle of Stalingrad (initially) enables the Germans to lower their combat losses (but a higher chance of starvation and imprisonment).

    “17.Casualty rates seem to decline during river crossings.”
    Berezina 1812 and Dnepr crossings 1943?

    “26.Attacker tank loss rates are generally higher than defender tank loss rates.”
    Not for Dubna and Prokhorovka.

    “Casualty rates are higher in summer than in winter.”
    The conditions for launching large Operations improve during summertime, this leaves room for higher combat intensity, especially in modern warfare.
    Attrition increases in bad weather and during Winter though.
    Casualties are also (obviously) linked to the duration of each conflict and the respective territory (e.g. the vast steppes of the Eastern Front or the Vietnamese/Cambodian Jungle). War in a higher industrialized country may lower the attrition rate (it may be antiproportional to the level of development but I have not seen any data on this so far).

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