Summary and Lessons from “On Combat”

On Combat—The Psychology and hysiology of Deadly Conflict in War and in Peace by Lt. Col. Dave Grossman and Loren W. Christensen (third edition from 2007) is a well-written, evidence-based book about the reality of human behaviour in life-threatening situations. It is comprehensive (400 pages), provides detailed descriptions, (some) statistics as well as first-person recounts, historical context and other relevant information. But my main focus in this post is in the advice it gives and what lessons the LessWrong community may take from it.


In deadly force encounters you will experience and remember the most unusual physiological and psychological things. Innoculate yourself against extreme stress with repeated authentic training; play win-only paintball, train 911-dialing and -reporting. Train combat breathing. Talk to people after traumatic events.

Disclaimer: While I have read most of the book I have skimmed or skipped some sections I didn’t found sufficiently relevant, applicable or new. These are mostly chapters in sections III and IV on warrior mind-set and history. I couldn’t make myself read the section about the will to kill. I have to note that Grossman writes very balanced overall. He does strongly motivate the need for warriors and peace-keepers and urges for a suitable mind-set. This is to be expected of a distinguished West Point teacher. Nonetheless does he do so without indoctrination or lies. He tells the scientific truth about the harsh realities of war and deadly encounters and where he ventures into speculative explanations he says so. Where he inspires (there is a bit of hero cult between the lines) he mostly quotes people from the field. He also holds laudable views about the effect of violence on children.

He starts quickly with the hard facts.

Arousal Conditions

Grossman structures physiological arousal into conditions based mainly on heart rate:

  • White (baseline bpm) calm, ineffective (“for sheep”)

  • Yellow (increased heart rate) alert and prepared (needed for fine motor control e.g. for aiming, mechanics)

  • Red (~120-140 bpm) optimum survival rate, at the top complex motor skill deteriorates

  • Gray—increasing deterioration but experience and training can compensate the set-in of Nlack

  • Black (definitely if >175 bpm) vasoconstriction, only gross motor skills, auomatic behavior, loss of perception

Condition Black

Black is the state you will be in if you are in a life-threateing situation you are not prepared for and this what a lot of section I is about:

You will definitely lose bowel and bladder control (except if you went to the toilet immediately before).

You will be scared literally speechless (because speech requires motor control). What helps is trained responses.

Vasoconstriction will shut down blood flow in your outer body layers. You will be white and not bleed from wounds but also lose any related motor control. Caution: You may bleed profusely when stress fades.

You will go on auto-pilot. You will do what you trained or visualized to do. You may freeze or fight or flee irrationally. You may go into a do-loop performing the last action dumbly repeatedly. What helps is training (see below).

Cognitive Distortions

You will most likely experience one or more of the following cognitive distortions:

  • Diminished sound and this can be very selective, esp. not hearing expected noises. The ear apparently can physically shut down within ms (such that no ear ringing occurs).

  • Intensified Sound

  • Tunnel Vision which may very seldom be combined with

  • Heightend Visual Clarity including memory of it.

  • Distorted Depth Perception

  • Sensory Exclusion in general, e.g. not feeling/​smelling/​tasting something, feeling no pain, feeling pains in different parts differently.

  • Sensory Overload e.g. from flashbangs can totally shut you down.

  • Slow Motion Time where everything seems to go slow and you have ‘time’ to act but if you are not prepared this may feel like Paralysis (because your body obviously doesn’t speed up accordingly). I was very surprised that this is apparently very real and research into this is going on (Grossman speculates about future pills to control this).

  • Fast Motion Time where you think slower.

  • Memory Loss for parts of the event or some of your actions.

  • Memory Distorions where e.g. your halluciations or fears are remembered as real.

  • Dissociation where everything seems to be unreal. Or where you experience to be out of your body.

  • Intrusive Thoughts that have nothing to do with the situation and distract from it.

  • Psychological Distortions where you focus on a basic emotional theme (my term) e.g. protecting others and puting their well-being above your own.

Basically your perception and memory can be trusted no more than a small childs. Possibly because you went down to that level of cognitive control. Only your unconscious competence will remain.

The theory put forward as to the origin and possibly adaptive function of these distortions is that some versions of these distortions are perfectly adaptive for predators (e.g. tunnel vision) and others for prey (e.g. visual clarity, intensified sound). And humans may have remaining potential for both.


What helps to act well in these encounters is training. Precise training. Repeated training. There are lots of proverbs in the book but I select this:

“Your brain will not ascend to the challenge, but descend to the level of training.”

Grossman gives lots of examples how a warrior or police officer should train but I will just give the corresponding advice for everyday people:

Innoculate yourself against stress by training some authentically dangerous situations. A very good idea is to play paintball as that is a very competitive situation that is behaviorally comparale to a deadly force encounter. Use this to self-program to win and get going. Do not ‘die’ in the paintball game. Set it up that everybody may at least continue after a few seconds ‘shock’. Also train to always back away and not to turn. Train in pairs.

People do not die easily in real life, you may loose 13 of your blood and there are survivors of even head and heart shots (you can act 5-7 seconds after hit in the heart and modern medicine will patch you together if they arrive fast enough, make sure they do). So you should not train yourself to ‘die’.

Train dialing 911 (or whatever your emergency number is; make sure to set-up your phone suitably) and give accurate reports. Do so in a situation with suitable arousal (e.g. after a heavy run or in the middle of the night or with gloves). Many people are not capable to even dial the number in an emergency because they lack sufficient control.

Train some routine manoevers you think appropriate like searching cover, making alarm noises (Bigger Bang Theory) or exiting the house.

Video Game and Violence

This is a very interesting aspect of the book. As said above Grossman urges precise life-like training to ensure effective acting which includes automatic killing. But he is very well aware that the same kind of training goes on in ego shooters. He proposes that youth mass killings (some mentioned in the book) were at least partly facilitated by the markmanship these video games provided. Today there are many recruts that aquire ‘super-human’ shooting skills within one firing range session—because they played ego shooter everyday. Same for the highschool killers: 8 kills out of 8 shots with only one training session with a real weapon.

And the worst thing is that even though the killers may have planned to kill only their offender they often continued with the next victim and so on as if in trance—as they ‘trained’ in the games. The only ray of hope is that these games train stopping if called to. May highschool shootings were actually stopped immediately simply by calling the youth to stop. Like “game over” in the game.

Grossman apparently runs and/​or supports campains banning or better restricting these games and also urges parents to reduce TV consumption esp. violent video. Children are drawn to violent media because knowing about violence is an essential survival drive.

UPDATE: Grossman is apparently misleadingly representing the facts about teenagers mass killings and teen violence in general.

Do Video Games Train Snipers? → No

Have teenager mass killings increased with Ego Shooter User? → No


Grossman shows that we cannot control the autonomous nervious system (directly) and that there are only two aspects of it that can easily be controlled: Blink and Breath. By controlling breathing one apparently has a strong feedback effect on the autonomous system. Slowing down breathing slows down the pulse. Grossman explains how Combat Breathing works and gives numerous examples of it’s success (but I couldn’t find a reliable study on this). Grossman also cites Lamaze Breathing as related.

The method in short:

  1. Breathe in through the nose counting to 4.

  2. Hold Breath counting to 4.

  3. Breath out through the nose counting to 4.

  4. Hold Breath counting to 4.

  5. Repeat 4 times.


After short experiences it will take some time for adrenaline to burn off. Physical exercise helps.

Afterwards you way experience reduced or increased appetite. And you may experience significantly increased sexual arousal (at least if a man) or a cessation of your period (if you are a woman). Both is normal but should be communicated clearly.

For very traumatic experiences you will likely need psychiatric treatment afterwards, esp. if the event took longer. The main variant is PTSD. What helps is stress innoculation (see training above) beforehand and professional debriefing afterwards (best repeated some times).


There is a section on lack of sleep. Sleep deprivation makes you as ineffective in life-threatening situations as if you were drunk. Caffeine helps bit. Nicotine doesn’t. Pain helps.

Warriors (and in general many people) often have performance anxiety dreams where their weapon or equipment (or their art) fails them.

Grossman explains that many battles were won due to psychology and the impression of power made played a larger role than the actual power. One major contributor to this is the ‘Bigger Bang’. What makes a bigger impression on the enemy is perceived as more powerful even though it objectively may not be so. Obviously a simple bias but as cognition is low in battle the effect cannot be countered easily. That is the reason muskeets were effective. They were loud and impressive whereas an arrow just went ‘twit’. Same with modern weapons. One exploding granade can have a much more fear inspiring effect than the ding ding of precision guns—despite killing less.

The chapter on war history included the short remark that most ancient battles apparently involved more show than fighting—until one side gave in. This matches up with a dissonance I had when reading Anabasis: I was surprised that Xenophons Greek had so little losses during their trek thru asia minor—despite many attacks. Apparently really little actual confrontation was need because of the superior performance of the greek.

The chapter on spiritual and moral aspects contained the interesting point that the commandment “Thou shall not kill” is probably better translated as “Thou shall not murder” (and is rendered this way in some translations). Apparently this view is backed by quite a lot of verses some of them by Jesus.

My own 5c

I experienced a Condition beyond Red twice in my life.

Once as a youth when I was beaten and kicked on the street, went on auto-pilot, covered in fear and had loss of memory and somewhat traumatic emotional associations with the event afterwards.

The second time as an adult. Due to a dangerous incident I spontaneously went into a protective auto-pilot mode in which I stubbornly continued to protected even when there was no danger. I still have relatively precise recollection of the second event and it is surprising who protective actions were deliberately planned but meta-level though and empathy were off—until they suddenly kicked back in.

My understanding of what happend and how it happend in these events became clearer due to the book.

To control my asthma I use a mix of breathing methods, one being Buteyko Breathing, another the breathing technique from the prenatal classes of my ex-wife. Now I also regularly use Combat Breathing e.g. to get to Condition Yellow in fencing.

ADDED: I acted on the advice in the book by training dialing 911 with my oldest (line disconnected). I also taught him the breathing technique.