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.