Jonathan Shay’s Achilles in Vietnam is an unusual book to encounter while thinking about wargame design because it is neither a military history nor a book about games. It is a study of combat trauma written by a psychiatrist whose work with American veterans of the Vietnam War led him to compare their experiences with the behaviour of Achilles and other warriors in Homer’s Iliad. Published in 1994, the book became an important contribution to the developing understanding of combat trauma and particularly to what subsequently became known as moral injury.¹ Shay’s influence in this area remains substantial, although later research has broadened and qualified the concept considerably.²

Shay’s central achievement is to move the discussion of combat trauma beyond the simple proposition that soldiers are psychologically damaged because frightening things happen to them. Fear, exhaustion, injury and exposure to death obviously matter, but Shay is equally interested in what happens when the moral framework within which soldiers operate begins to collapse. His Vietnam veterans repeatedly experienced situations in which their expectations concerning leadership, loyalty, justice and acceptable conduct were violated. The resulting damage could involve anger, grief, guilt, distrust and a loss of confidence in institutions and other people. Shay subsequently developed this approach into the concept of moral injury, with particular emphasis upon the consequences of failures by legitimate authority in situations of serious consequence.³

The comparison with the Iliad initially sounds as though it might be little more than an interesting literary device, but it proves to be one of the strongest elements of the book. Achilles is not treated simply as a heroic warrior whose battlefield exploits can be separated from everything around them. Shay instead examines the deterioration of relationships between commander and subordinate, the importance of comradeship, the effects of losing a close companion, the growth of uncontrolled rage and the eventual destruction of normal restraints upon violence. Modern scholarship has continued to recognise the usefulness of Shay’s attempt to use twentieth century combat psychology as a means of reconsidering the behaviour of warriors represented in ancient literature.⁴

This is also where Achilles in Vietnam becomes particularly interesting to the wargame designer. Most rules are very good at modelling weapons and comparatively poor at modelling people. We calculate ranges, rates of fire, armour penetration, movement distances and casualty probabilities with considerable enthusiasm, while morale is frequently reduced to a die roll made after a unit has suffered a predetermined number of casualties. A unit passes and continues fighting, or fails and retreats. Shay suggests that human behaviour in battle is considerably more complicated.

Combat effectiveness depends upon relationships as much as weapons. Soldiers may endure extraordinary danger because they trust those around them, believe that their leaders are competent and regard their actions as having some legitimate purpose. Conversely, combat effectiveness may deteriorate even when casualties remain comparatively light if leadership fails, cohesion collapses or soldiers conclude that the system within which they are operating has ceased to make sense. This distinction is particularly useful for designing morale and command systems because it suggests that morale should not simply be treated as another form of accumulated physical damage.

There is an equally important lesson concerning unit cohesion. Shay places enormous importance upon the small group and the bonds formed between soldiers who depend upon one another for survival. The loss of a close comrade can therefore have consequences considerably greater than the numerical reduction of a unit by one man. For wargame rules this raises an interesting design problem. Ten casualties inflicted individually across ten units need not have the same psychological effect as ten casualties concentrated upon one closely integrated group, while the loss of a commander, respected veteran or other central figure may produce effects entirely disproportionate to the physical loss involved.

The discussion of rage is perhaps even more challenging for conventional game mechanisms. Military rules usually assume that morale deterioration makes soldiers less dangerous because they become reluctant to fight. Shay demonstrates why this assumption is incomplete. Psychological disintegration can sometimes produce withdrawal and paralysis, but under different circumstances it may encourage uncontrolled aggression. A unit suffering severe psychological stress might therefore become temporarily more violent while simultaneously becoming less militarily effective. Such troops might attack recklessly, ignore orders, expose themselves unnecessarily or employ violence that contributes nothing to achieving their tactical objective. That is a far more interesting model than simply applying a negative modifier to a morale test.

Leadership consequently deserves more attention than the traditional command bonus. A commander should not merely provide an additional point on a die roll because leadership influences whether soldiers continue to trust the organisation itself. Poor orders, unnecessary casualties, abandonment and perceived injustice can damage cohesion in ways that cannot be repaired merely by replacing the officer figure. This aspect of Shay’s argument has retained particular importance in later discussions of moral injury, which distinguish between trauma associated primarily with threat and trauma involving moral judgement, responsibility and betrayal.⁵

There are nevertheless significant limitations to the book. Shay is working primarily from clinical experience with American Vietnam veterans and deliberately uses Homer as an interpretive framework. Neither source should automatically be transformed into a universal theory of soldier behaviour. Armies differ enormously according to culture, period, recruitment, training, ideology and expectations of authority. The psychological experiences of an American infantryman in Vietnam cannot simply be projected backwards onto a Roman legionary, Napoleonic grenadier or medieval retainer without considerable qualification. The comparison with Achilles is illuminating precisely because it encourages questions rather than because it proves that combat psychology has remained unchanged for three thousand years.

There is also a danger in taking moral injury too far as an explanatory concept. Subsequent scholarship has developed definitions that extend beyond Shay’s original emphasis upon failures of authority and examine situations in which individuals believe that their own actions have violated deeply held moral standards. Researchers also distinguish moral injury from post traumatic stress disorder rather than regarding the two as interchangeable.⁶ This matters because a wargame designer who turns Shay’s ideas into a universal morale mechanism would be making exactly the mistake that the book should encourage us to avoid. Human responses to combat are conditional rather than mechanical.

For writing wargame rules, therefore, Achilles in Vietnam is most useful as a challenge to assumptions. It encourages the designer to ask whether morale is really being modelled or merely represented by a convenient probability test. It suggests separating fear, cohesion, leadership, exhaustion, grief and aggression rather than hiding all of them inside a single morale value. It also suggests that command failure should have consequences beyond preventing a unit from activating and that the psychological importance of casualties may depend upon who has been lost and under what circumstances.

None of this means that every tabletop game requires a detailed psychological model. Indeed, attempting to represent every element identified by Shay would probably produce an unplayable game. The designer’s task remains one of abstraction. The important lesson is deciding what should be abstracted. If the game is concerned primarily with weapons and manoeuvre, a simple morale system may be entirely adequate. If it claims to represent command friction, unit cohesion or the behaviour of soldiers under sustained combat pressure, however, then Achilles in Vietnam provides a powerful reminder that casualty percentages alone are a very poor substitute for human behaviour.

I found the book particularly valuable for that reason. It does not provide mechanisms that can simply be lifted and inserted into a set of rules, and attempting to do so would misunderstand both Shay and game design. What it provides instead is a different way of thinking about what happens between the neat numerical categories that wargamers naturally create. Soldiers do not merely accumulate casualties until reaching a breaking point. They operate within networks of trust, obligation, friendship, authority and belief, and those relationships can themselves become casualties of battle.

For anyone writing wargame rules, that makes Achilles in Vietnam worth reading well outside its original clinical purpose. It will not tell you whether a morale test should require a seven or an eight, but it may persuade you to ask whether you should be making that particular morale test at all.

Footnotes

1. Jonathan Shay, Achilles in Vietnam: Combat Trauma and the Undoing of Character (New York: Atheneum, 1994).
2. Victoria Williamson, Sharon A. M. Stevelink, and Neil Greenberg, “Occupational Moral Injury and Mental Health: Systematic Review and Meta Analysis,” British Journal of Psychiatry 212, no. 6 (2018): 339–346; Brett T. Litz et al., “Moral Injury and Moral Repair in War Veterans: A Preliminary Model and Intervention Strategy,” Clinical Psychology Review 29, no. 8 (2009): 695–706.
3. Jonathan Shay, “Moral Injury,” Psychoanalytic Psychology 31, no. 2 (2014): 182–191.
4. Elizabeth Baynham, “Alexander, Combat Psychology, and Persepolis,” Antichthon 35 (2001): 30–44.
5. Shay, “Moral Injury,” 182–191; Litz et al., “Moral Injury and Moral Repair,” 695–706.
6. Simon Frankfurt and Patricia Frazier, “A Review of Research on Moral Injury in Combat Veterans,” Military Psychology 28, no. 5 (2016): 318–330.