I was born in Dublin to an Irish father and an English mother, both of whom, I can say with affection, are old hippies. Dad is a psychotherapist and tour guide and Mum is an abstract artist and housewife, though like many people from an alternative background they have changed vocations many times during their lives. (Among other things, Dad has been a decorator, a stunt double, a scriptwriter and a pilot.) They both have a big interest in co-counselling, and Mum is very spiritual: she followed an eastern spiritual discipline, is a regular churchgoer and continues to sing in a local gospel choir. She made her own wine and jams and took us picking berries on country lanes when no one else was doing it.

My parents were never much interested in material things. (Just as well: they couldn't have afforded them.) But there was always art in our house, and I was taken to exhibitions and galleries from an early age, and rock concerts too. There always seemed to be interesting people visiting – poets, painters, sculptors, scriptwriters and spies. People who lived on the fringes.

My parents came from a Protestant background, but I was enrolled in a multi-denominational primary school. Self-expression was encouraged. I wore Doc Martens and tie-dye shirts, with tie-dyed long hair to match; I think my parents were pleased. Their outlook was to encourage the individual, rather than be conformist.

But my parents' enthusiasm for self-expression resulted in something they didn't expect. I became more and more interested in toy guns and weapons.

They introduced an arms control policy that ended my plans to be the most heavily armed kid on my estate. But it didn't put me off weapons. Useless water pistols were handed in for decommissioning. But in their place, and at considerable cost in pocket money, I brought in the most lethal-looking toy weapons I could find: M16s, sub-machine guns, pistols – anything that appeared deadly. When my friends came over, we set about re-creating battles in the hedgerows and on the lawns of my housing estate. Sloped hills covered in bushes became fortresses for storming, hedges became perfect fire-support positions and, best of all, the small clusters of mud that dried at the bottom of these hedges were perfect "muck bombs" that disintegrated like a grenade when hurled at an opposing fighter. For me it was paradise, and as much of my time as possible was spent trying to find militaristic eight-year-olds who were up for chasing glory in the streets.

My brother Match was born three years after me. My initial shock at this new rival gave way to excitement at the prospect of a new section commander who wouldn't disobey orders. Our sister Becky came three years later, and while Match was always up for militarism, she preferred football, making a brave, if reluctant, goalkeeper.

My obsession with the military was accompanied by a love of military history. For as long as I can remember, I have been fascinated by the second world war. My parents were mystified, but found themselves taking me to visit the Imperial War Museum or military museums in Aldershot, when we visited relations in England. Once, in the early 90s, we rolled into the excellent Parachute Regiment museum in our old Irish-registered car. The Paras on the gate understandably freaked out. That day I played beside an old Dakota airplane. Twenty years later, I would have my photo taken under it as a potential Para recruit.

My dad, being Irish, had reservations about the British army, particularly after Bloody Sunday. He had marched in London against the actions of the Paras that day. He espoused Churchill's idea that jaw-jaw was better than war-war. A friend of the family once warned him about me: "I hope he understands it's about killing people." I did.

As a family we've been through our ups and downs, like all families have. As a teenager, I was in a bad space and got into trouble with the law for possession of ecstasy, and that was a difficult time for everybody. For the most part, my parents stayed supportive, and I turned my life around. The other day I saw a quote that really brought that time back to me: "A child needs your love the most when it deserves it the least."

Discussions about my joining the army were supportive rather than confrontational. By then, my interest in the military had been a part of my identity for a long time, and my parents were still committed to allowing me to do what I wanted. Beneath their outward support, I could feel their deep reservations. But, to be honest, I ignored them. Before I joined up, the whole family marched in Dublin against the Iraq war. I was doubtful about the invasion, and so were army officers I had met. I didn't think marching ran counter to a future chosen career in the army; you can express your opinion before you join and you can express your opinion after you leave, but not while you're in, and that's the way it should be.

Initially, my parents didn't understand some of the positive aspects of military life, but they were glad to see me happy and fulfilled, doing a job I always wanted to do. Their cynicism remained, though it was usually hidden from me. On the steps of Sandhurst, after I was commissioned, my mother remarked to Dad: "They give us lunch, and we give them our sons."

This would only have been true, I felt, if I'd been conscripted. A lot of families don't "get" the military until someone joins, and I think a lot of the population are entirely segregated from the forces. It's best not to hold to firm opinions one way or the other. A lot of my civilian friends thought I would completely change when I went into Sandhurst – that I'd end up an automaton – but it's not like that. It's about developing character and leadership. If anything, I think my military experience has made me a more open and balanced person. I believe that my parents, and Match and Becky, would say the same.

I joined another family in 2006, the Royal Irish Regiment, and I am honoured and humbled to have served for over four years with their great soldiers from north and south of the Irish border. It's amazing how close you get not only to other fellow officers, but also to the rangers you have been lucky enough to command in Afghanistan. After five months in Sangin, these men are your family. You would die for them.

It was difficult saying goodbye to my blood family when I left for Afghanistan. I made sure I told each of them that I loved them in case I didn't come back. When they drove away from the barracks in their blue Dublin car (they told me later) no one spoke for 10 minutes. Then Match broke the silence. "Did you see the way he looked at us?" Dad says he felt the moment was really chilling. But I wasn't sure if I'd be back, and in truth I nearly wasn't. I think everyone on the frontline knows the feeling. Once it got hairy out there, and people were being killed and maimed regularly, I shielded my family from the details – just saying: "It's busy." But they watched the coffins coming back on the news. At one stage my platoon air assaulted with the Paras into a Taliban stronghold in Helmand. We fought for 13 hours. A sergeant major was shot dead right in front of me and bullets missed my head by a hair's breadth. Another time I sat on an undetectable bomb for half an hour. I don't know how I'm still here.

I remember the emotion in my mum's voice when I rang to say I was OK and off the frontline and coming home. It was then I realised how selfish I had been. I once tried to convince an excellent corporal, who had fought in Sangin in 2006, not to leave the army. One of his arguments was that he "just couldn't put his family through that again". As a green second lieutenant, I couldn't even pretend to understand, let alone counter him. I understand now. It's one of the reasons that influenced my own decision to leave the army.

The Royal Irish have recently deployed on their third tour of Helmand. Whatever elan and heroism may be shown on the battlefield, it would not be possible without the fortitude of the families left behind. When I got back home, one question I was inevitably asked enraged me: had I killed anyone? It really showed me the difference between civilians and soldiers. My parents were among those who didn't ask, but I told them I hadn't, which was true. As a platoon we had life taken and we took life. Such is war. They were trying to kill us and we killed them. I do not carry an iota of guilt, though I understand the Taliban's position too.

The guys from the platoon are still close, and we keep in contact and see each other when we can. We have that bond – whether you still serve or have left, it's always there. They are still my family. I am still very proud that I served in the infantry, and I'm also proud that I struck out on my own path, whatever my parents thought at the time, or still think.

When I have kids, if they want to play with guns, I'll let them. For good or bad, there is a natural tendency for a small number of males to be drawn to a martial lifestyle. To deny it does not help anyone. A lot of people become artists or writers to be different from their parents. I did that in reverse – opting for a more conventional career. In choosing an army officer's life, I was aware that it was at odds with much of my folks' world view, and their view of war in particular. They were basically pacifists, while I was actively looking for the challenge of leading men in war. We had, and still have, different views about conflict, politics and "the system". I'm more pragmatic and centrist, while Dad likes to indulge his lefty fantasies. We don't have massive rows, but we do disagree about what motivates the players on the world stage. Mum is relieved that I've left from a safety point of view, but she says of the whole experience: "You were brought up with your parents' voices, so it's important to hear your own voice and move out into your own life."

Patrick Bury is a former captain in the Royal Irish Regiment who served in Afghanistan. His memoir, Callsign Hades, is published by Simon & Schuster, £18.99. To order a copy for £13.59 with free UK p&p, go to theguardian.com/bookshop or call 0330 333 6846

Richard Bury: 'We had to support our son'



I never challenged him about it, but I had deep reservations. Being Irish and having lived through the trauma of Northern Ireland in the 70s and 80s, I had misgivings about the British army. I'm not a pacifist – I would always have an army for defence, but not for colonial aggression. In Toronto, I marched against the American invasion of Vietnam; in London I marched against Bloody Sunday.

Sofia and I did talk about his decision to join the army and we probably ended up laughing about it – where did we go wrong? But I was still cynical of it. We believed an element of training was to break them psychologically, which went against the way we brought our children up – to think for themselves. Patrick and I didn't have big political discussions about the war. I felt it would only complicate things and make him feel he was compromised in some way so, unusually for me, I bit my tongue.

When he was away, I became hypersensitive to any mention of the army or what was happening in Afghanistan. When I heard the words "another British soldier ... " I always froze. There is this moment of relief followed by awful guilt when you realise what other parents will be going through.

We knew that if anything happened to him, the Ministry of Defence would tell us before it was released to the media, and because of the time difference, this could be a phone call in the middle of the night. He had been in Sangin for about a week when the phone rang at 2am. I remember saying to myself over and over: "This is not it, please, this is not it." It was one of the other kids' drunken friends, but that was probably the worst moment.

We spoke to him every week, and kept in touch by email. He never told us what was going on, he would just say: "It's a bit tough." When he came home everybody wanted to know if he had killed somebody. I didn't have the balls to ask him, and I think a bit of me didn't want to know. When I read his book, I spent a lot of time crying because I was so shocked at what his work had entailed. I was away when Sofia rang to say she had spoken to Patrick and that he was off the frontline. She was in tears and I just felt enormous relief. As told to Emine Saner