How the horrors of war nearly destroyed me

War's most dreadful secret, banal and terrible at the same time, is not that men kill - that much is obvious - or even that many men enjoy their killing. That, too, has been well documented. It is more insidious than that. There exists a widespread envy of those who kill, and especially those who kill and kill again. There is a bitter resentment among men when others claim their kills, or their kills are denied. That deems some men "luckier" to have the opportunity to kill more than others.

Soldiers bitching. Another outpost, infested with rats that crawl across useless ceiling ducts that are connected to nothing in a former police station half-ruined by a bomb. The talk is about the young Texan lieutenant who has just left to lead a Small Kill Team on an overnight ambush, palefaced and tired. Top of his class at school, the soldiers say with pride. From what they say it is evident he likes killing and is motivated by opportunities to kill. His men like and respect him, admire his bravery, but sitting on their cots they resent him grabbing all the opportunities to rack up his kills. An activity so full of paradoxes, its meanings are hard to mine and even more difficult to understand. Killing, as Joanna Bourke explains in her study of combat, An Intimate History of Killing, for very many men is an exciting and pleasurable activity as well as a taboo. Being exciting, it is hidden on return to a civilian life that regards permissive killing, even in the high heat of conflict, as something "to be done", an experience to be endured. But it is different in proximity to the battlefield - among your "buddies" - where all ordinary rules are deliberately suspended. There it becomes obvious that the business of killing is easily assimilated into the story-worlds that define men's lives. It is integrated into all the other stories that I hear when the men are sitting in their hooches, or round their Saturday night barbecue pits with their cigars, drinking non-alcoholic beer or Gatorade with a shot of illicit spirits occasionally mixed in, after smoking a discreet bowl of hash. Then they talk about sex and cars and films; holidays and children. And sometimes combat and killing.

I am sitting with two soldiers on a base near Mosul in northern Iraq. "Don't use our real names," says DC, a handsome paratrooper from the New York suburbs, a good enough soldier, it seems, but with a troubled history that has seen him busted down from sergeant and made up again. "I don't fucking care," his friend Andy interrupts, grinning a spacey smile: "I'm so far out of my fucking bubble." I am listening to their theories of life. Mainly they involve emotionless sex and racing cars and motorbikes. They talk about how to tune the engine of a Harley, about drag bikes, crashes and the tactics for midget car racing. They tell me how fat girls are always a dead cert, and best picked up at the ice-cream counter at Wal-Mart at 2am. "Those are the ones you know who really hate themselves," says DC. About the competitions back at their home base in Texas to see who can pick up and fuck the fattest women. "We had a ton, once, in the same room," says DC, grinning. He whistles, trying to see if I am shocked. About queuing to fuck the same woman with your buddies. Rotisserie, they call it. They talk about getting wasted back home, and driving pickup trucks with oversized wheels, and fleeing from the cops. Finally, the conversation turns to Iraq and getting stoned and heading out into the Red Zone behind the sights of a big gun, weaving together the strands of sex and violence until all human life seems as consumable as different cuts of meat.

It is the first time that any of the American soldiers I have come across have spoken directly about taking drugs, although I have heard rumours. The random drug tests keep it underground, discreet, unlike Vietnam. But they are off duty and garrulous at the end of a day in which their unit has not been required to go outside the wire, drinking coffee at one of the cafés the army has placed on the bigger bases. Most of the soldiers I talk to want to get out of Iraq as quickly as they can. Not DC. "Why are you in such a fucking hurry to get back home?" he demands of his friend. "What's back there? Nothing. This is it," he says emphatically. "Ain't nothing better in the world. Take a big hit on the bong and then get all dressed up and get behind my gun. And then it's: 'Come on, fuckers, fire at me', so I can shoot up the streets."

There is a game with guns I know some of the young soldiers play in Iraq called "Do you trust me?" An unloaded weapon is pointed at the head. The trigger pulled. Not Russian roulette, just a buddy game with guns. The point is that people forget to clear their weapons and accidents happen. That's what the question means. I never see it. It is too private a ritual for outsiders. Knives, however, are ubiquitous and visible. I am aware, all of a sudden, of the same knife everywhere. I see it clipped into jackets and combat pants. One afternoon I stop to watch a group of soldiers trying to throw and stick a couple of the blades into a sheet of plywood that they have laid against one of their CHUs - the containerised housing units that have been dragged into the country, stacked on the back of trucks. They are in shorts and trainers, a bunch of giggling kids, jumping up and squealing to protect their feet when the knives - inevitably - bounce back towards them off the hard, compacted wood.

Peter Beaumont at war.

On another occasion a smart and studiously polite woman soldier shows me her knife. She says she bought it after she came across graffiti in one of the plastic porta-potties outside the command centre where she works announcing that the writer "would like to fuck" her. She tells me she tried to scrub it out. Three times. Three times it returned, the letters creeping across the plastic. "I know it is someone I work with," she explains. "It feels like I'm being stalked." So she went to the PX military store and bought two knives, sliding one blade inside a desert boot and another into her pocket.

After a while I want to handle this knife, and get a sense of its potential. But I am reluctant to ask to look at one, embarrassed. The alternative that I settle on is to buy one from one of the warehouse-sized stores to be found on the larger bases that sell everything from chewing tobacco, DVDs and snacks to bras, cars and televisions. I find the knife in an aisle selling military equipment, buckles, badges and rucksacks. It comes in two sizes and I choose the smaller, not certain it will be legal to take it home to the UK.

As it turns out it is a Special Forces tactical knife, designed by Kit Carson, a name that means nothing to me. But when I look it up on the internet later, I see it described as a "classic design", offered for sale alongside other blades whose names I do recognise - fetishised little objects from novels about crime and serial killers that I have read, such as the Spyderco blades beloved of Hannibal Lecter. It feels like an act of transgression buying this object, and I hide my new purchase at the bottom of a basketful of Pringles and Gatorade, expecting to be challenged. I am not sure why, but I fear that I have crossed over into the world of people who own blades designed for injury and death. Fiddling with the knife, back in my CHU, it is the colour that bothers me. The bare, black metal of the blade and handle is unsettling - as if intended to be hidden and secret. Its stark utility - an edge and handle, nothing more - contrasts with the knives I have owned in my adult life which have all been ambiguous in nature, fulfilling multiple roles: Swiss Army knives and Leathermen, or knives with spoons and forks attached that break down into rudimentary dining sets. This is a very different kind of blade. I can see immediately that it is a well-made knife when I take it out of its packaging. I tell myself it will be useful for mountaineering - a sturdy, light and compact tool, good for cutting abseil slings, the sharp blade excellent for camping and picnics. I also know that is not entirely its intent. It talks of a different kind of functionality.

Folded into its curving black frame, the knife is 10cm long, the blade 3cm or so in width, tapering at the end to form the chiselled point of a dagger. I run my thumb over a set of deep saw-like serrations so sharp I can feel the points tugging at my skin. The whole effect is shark-like, sleek and full of teeth, so that I wonder whether it was intended in its design. Playing with the knife, I discover that one half of the thumb guard, which I had taken to be part of the handle, in fact forms part of the blade, fashioned so that the knife can be flicked open to the locked position with a quick push of the finger, swivelling on a pivot. It is not a flick knife - there is no spring - but if I flick my wrist in the right way, it will swing smoothly open and snick into its lock. It is an object of a stark simplicity, long and strong enough to punch through muscle and gristle, to find an artery. Sharp enough to cut a throat.

But there is a mystery here. No one in Iraq uses a knife to fight. No one wants to get that close when they can blast Iraqis at a convenient and safe distance with weapons that have made killing people simple. Yet the knife exerts a peculiar fixation, far more so than the soldiers' personal weapons which are carried like tools, useful but invisible despite being in plain sight. I see men run with them during PT, take them to the showers and cinema and church, prop them by the table during meals. There are some men - "geardos", the other soldiers call them - who lavish attention on their assault rifles, weighing them down with additional gadgets bought from magazines and the internet - special sights and extra torches. They are the minority. The knife is different.

For earlier generations of soldiers the bayonet was the fetishised instrument of violence, more fantasised about than actually employed. But cultures change. Now it is the Special Forces dagger that is the badge of close and personal killing, symbol in the military imagination of the true warrior ethos.

In war all life is negotiated around weapons. Societies are reordered into sharply defined new hierarchies: into those who have weapons and those who have not. A man with a gun can walk to the front of the bread or petrol queue. With his militia friends he can take over a petrol station if he likes and reorganise the distribution while skimming money off the top. With a rifle you can order a woman to have sex. Weapons redistribute wealth through "taxes", protection rackets and straight theft. Scores can be settled, under the cover of generalised violence.

A gun can be a lever in the political system. An armed group can take over a hospital ward, and later a whole hospital, as happened across Iraq, thus grabbing control of a key social provision for a political party. Having a gun confers small benefits too. In the Baghdad traffic jams (the izdiham) the way through is cleared by those who have weapons. A new topography is imposed upon the city by armed checkpoints and men with guns, which ways are open, which ways closed. Weapons censor, blocking out argument, debate, verbal exchange. Those with guns can speak. They have opinions and deliver orders and instructions. Those without are required to be silent.

Early on, in the first few weeks after the fall of Baghdad, a US soldier pulls a rifle on me as I try to reach the Sheraton hotel, the entrance to which he is blocking. I argue that I am staying in the hotel and that the car park, which he is preventing access to, is where I leave my car for safety. But he is new to the detail. Perhaps a little dumb and lacking in confidence, a youth for whom possession of a rifle is a replacement for thinking. I try to get him to turn around to see the other cars parked beyond the wire, but he is not listening. I can see his face through the windscreen, angry and scared because I am not doing what I'm told; because I'm in breach of the unwritten contract between the armed and the unarmed. He presses the weapon almost on to the glass in front of me. He is uncertain, shaky, and shuffles to get a better, wider firing stance, his hip pushed into my car's front bumper. The sights obscure his face, until all that is left is the visible fact of the gun, the worn "o" of the barrel's end that is echoed in a little, desperate, deflating "oh" inside of me when I realise that he might really fire.

The mere suggestion of a weapon is sometimes enough to trigger the same unsettling emotions. It is not the sensation of contact, the wild, druggy adrenaline rush under fire. Instead it is fluttering and flat, a sense of abruptly being diminished. Like the moment of hearing tragic news about a friend, as if all possibilities had been at once extinguished.

The knives I fear most are out in the mahalas, Iraq's dreary and dusty neighbourhoods that sprawl, massive and uniform, out of its urban centres. They are not the toys the American soldiers play with, dreaming their martial dreams, but the blades used by a tiny minority of Iraqis, the head choppers allied to al-Qaeda in Iraq, who employ butchers' knives made for slaughtering sheep and cattle to decapitate Iraqis and foreign hostages who fall into their hands. They are beheadings that exert a fascination on many Iraqis, unexplainable either by the Qur'anic exhortation to "smite the infidel in the neck", or as political acts designed to inspire terror through the horror of the spectacle. For some who watch them, collect them on their hard drives, it is clear they do have a political and religious meaning. But most who watch them in the internet cafés or who save them on their telephones across Iraq do so because they want to see a killing.

I avoid these grotesque performances until one day, to demonstrate a point, an Iraqi guard at a human rights organisation is called in to show me one of the clips saved on his mobile phone. I am supposed to be watching the murder of an Iraqi woman, but as he cups the phone in his hand and presses play to reveal a jumpy and bleached set of images, it is clear that the hostage is a dark, smooth-skinned man with faint, fatty breasts. What I am seeing is the decapitation of a Nepalese hostage in 2004, one of 12 murdered by the same jihadi group.

The video moves quickly to the murder. I tell myself at first that I am watching it for journalistic reasons. But I understand the curiosity as well. There is in these images a horribly compelling appeal. Perhaps it is the knowledge that in a few seconds a life will end. I wonder about the quickness of it and the pain. I am curious about the killer too - whether his hands will shake with excitement or with fear and fumble it.

A man lies on the floor, shirtless. His hands are bound behind his back with a broad white cloth. The same cloth, bloody on one side, is bound over his eyes. A second man in combats, his face carefully concealed by a cap, bends down over the prisoner. Quickly and methodically he begins to cut his throat. But what stays with me is not the dying hostage's last moments, breathing through a severed and quivering neck, nor the moans not the unreally red arterial blood, not even the theatrical dumping of the head. Instead it is the killer's use of his knife. It is a perfunctory sawing that probes deeply at the victim's throat as the executioner holds his head, looking for tendons and muscles to sever.

It is too easy for such a dreadful act: like skinning fish, or a butcher cutting fat off meat. I think: murder should be more emotionally charged, angry and physical, exultant or fearful, not this offhand snipping and slicing. I realise too that I have seen this before, watching the father of a Palestinian family cut just this way through the throat of a startled, hobbled ox held by his sons on a Gaza pavement, slicing and digging, to bleed it for a feast.

In the end even those of us who do not carry weapons are forced to address the meaning of their use. Two guns are sitting in an Adidas sports bag on my bedroom floor in the Hamra Hotel. It is later - much later - in the war. As it gets ever more dangerous, I accept that if I wish to work unembedded no option remains but to hire armed local guards to ride with me. It is an uncomfortable decision, not least because I have no illusions about whether two guards will make an ambush any more survivable. What is clear is that when everybody else has guards, not to have them marks me out as the soft option for any would-be kidnapper.

I employ Ayman and Thair, and a second driver to follow in a "chase car". At the day's end, the two men tuck their pistols in their waists, shake my hand and prepare to leave. They don't want to carry their rifles, which are illegal without a proper permit, back and forth to work each day. So Ayman, the older of the two, delivers the sports bag containing the two weapons to my room for the night. After a while I begin to feel that the weapons sit in my room with an unspoken permission attached to them: if things go very badly wrong, then use them. Except that I do not want anything to do with the guns. Even having them in my room instils in me a deep sense of uneasiness. I feel embarrassed by their presence, as if they were porn mags beneath my bed.

I did not always feel this way. I learned to shoot at school as a cadet. Then, guns seemed exciting and glamorous. To fire them as a 15-year-old boy was to enter a club with a small membership. My school, founded by Henry VIII, had a little range round the back of the bike sheds, stacked with sand, where we could fire .22 Martini rifles of first world war vintage and older - bolt-action rifles with wooden stocks polished from generations of handling. Later we were given Lee-Enfields, and on a trip to an army training camp in Cornwall we were allowed to fire pistols and sub-machine guns and given blank rounds with which to crawl among the steep-faced dunes in a mock attack that ended in the equally mock execution of my history teacher.

I feel the AKs in my room, morosely silent visitors. Although I do not like touching guns as an adult, I know how these weapons work and their peculiarities. I have seen them fired and stripped and fought with. I have seen them used as hammers and levers to break locks and doors, used as clubs and barriers. Mostly I have been afraid of them. I have had their bullets shot at me, or travelled in pickup trucks with bored teen agers who do not know how to make the weapons safe. I know that the safety catch is counter-intuitive, going from safe to fully automatic and only then to single fire. I know, too, that they have a reputation for recoiling heavily, so that when fired on fully automatic the weapon tends to climb away from the target after the first three shots.

One night I cannot sleep and I feel that it is the guns that are responsible. It is a bad time in Baghdad and the conversation in the Hamra Hotel has come round to what-ifs: how long the few journalists left in the hotel will be able to continue working and what would happen in an evacuation of the hotel; how long the security on the perimeter could hold out before the Quick Reaction Force could mount a rescue mission from the Green Zone. The times talked about seem long. The guns beg a question that I understand must be resolved.

It is past 1am. I slip out from underneath the thin, uncomfortable sheets to stand in my bare feet. I pull a chair to the centre of the narrow room and set it facing the door. My bare back glues to the wooden frame as I sit there in the dark, looking at the faint lump that is the bag - until I drag it to me and unzip it. By now, my eyes have acclimatised to a purple darkness illuminated only by the light outside my window. It is enough to see the worn black metal and cracked wood, the grey duct tape wound round the doubled magazines to hold them together for rapid changing of the clips.

Gently I take one of the rifles from the bag and lay it on my lap. I can smell the faint tangy odour of oil. I let it sit there for a few seconds - no more. But then I know that it is done. As I return the rifle to its bag I understand for the first time in over a decade of covering conflicts that I would use this weapon if I had to. I know too the implications of that realisation - that my time covering wars is grinding slowly to an end. I have been compromised by fear. Corrupted by what conflict means.

About the author

Peter Beaumont is the foreign affairs editor of the Observer. He joined the paper in 1989 and has reported extensively from conflict zones including Africa, the Balkans and the Middle East, and has written widely on human rights issues and the impact of conflict on civilians. He has received several awards, including the One World Media Award, the Amnesty International Media award, and the George Orwell Prize for Journalism.

Postscript: April 2009

It is not always the big things. Last September, on the eve of an ordinary assignment, I woke up and realised I never wanted to see an airport again. I didn't want the smell or the sight of them. The grey, boring moments spent waiting in departures lounges I felt had eaten up my life. I didn't make it to Heathrow.

It was a crisis that had been building for over a year. In my last year reporting from Iraq, something had happened. Rather than seeking the most meaningful stories, I had slipped into chasing the most dangerous ones. And in the process I had become someone I didn't want to be. Not someone who wrote about the consequences of war, but someone who had become part of its logic.

When, on the last day of what would be my final trip in 2007, a car bomb exploded in front of the vehicle that I was in, it didn't seem to matter. It was, I rationalised at first, an ordinary event in the country that is in conflict. Except that it did matter, in ways I could not then imagine. I dreamed about explosions. I jumped at slamming doors. I experienced periods of recklessness and of stultifying dissatisfaction. Two months later I found myself explaining why I never wanted to go back to Iraq again. And later still, why I had had enough of travelling.

The writing of The Secret Life of War was part of the crisis. In two-and-a-half years of working on it almost every day, I'd come to expect that when it was done, I would have written my last words about the conflict. But there was no sense of catharsis, no sense even of completion. Now at least I am happy with it for what it is, an attempt to deliver a personal, tentative and partial description of aspects of the experience of war.

But I am travelling again. This time I made it to Heathrow and Sarajevo. In January I covered the violent aftermath of the conflict in Gaza, and plan to return to finish a long-term project. I am not certain I understand fully what has changed. But I am no longer the person who came back from Iraq. Less confident and more careful, I have, I hope, reconnected with the person I once was - a person who cared about the victims more than the rituals of war.

I have realised too that everyone who is engulfed by war - willingly or not - loses something. For me that has been a connection to ordinary life, to my children and friends, and habits that, as I grow older, I have learned can never be repaired. In that knowledge, perhaps, there is a balance to be found.

• The Secret Life of War: Journeys Through Modern Conflict, by Peter Beaumont, is published by Harvill Secker, £16.99. To order a copy for £15.99 with free UK p&p, call 0330 333 6847

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