I have lived through 60 years of comparative peace, but my life has been touched by war. I do not mean in a direct way. I was born in 1943 and evacuated to Cumberland, so I had an even smaller part in the downfall of Hitler than Spike Milligan. I can remember no falling bombs, no droning aeroplanes. I have never known the terror of bombardment, of battle; not witnessed for myself the savagery of warfare. But all the same I have seen what war has done and can do to families, to lives, to homes.

I grew up in bomb-blasted London. Some of my earliest memories are of playing among the ruins of bombed-out houses in our street in Earl’s Court.

There were no playgrounds or swings or seesaws for us, but cliffs of crumbling masonry which I climbed as high as I dared to reach the pigeon’s nest and steal away the marble-white eggs; there were dank dark basements which I made into dens, filling them with broken furniture and crockery and covering the floor with brown lino. Here I made the first home of my own, my very first private place.

Rationing for me was simply part of the excitement of shopping - no more. I was not aware then of the deprivation of those post-war years. Deprivation universally shared is hardly noticed by children, I think. Of course, those years were not post-war to me at all. Growing up is a busy time, and I was too busy to take much notice of how things were. The house was cold. So were all houses. The milkman’s horse ate out of a sack he wore around his neck. Steamtrains chuffed steam and I loved the smell of it. Smog was really fun. Chilblains itched.

But I did take more and more notice as I grew up of the suffering caused by the war. Any insights I might now have come from stories told round the kitchen table about friends of my parents killed in some distant battle or perhaps maimed by a mine in Italy, or another torpedo in the Atlantic; one incarcerated in a prison camp in the Far East who returned home looking like a ghost; another terribly scarred on his face and hands when his Spitfire was shot down, scars I was told not to stare at but which fascinated me and horrified me at the same time. There were stories of heroism - an uncle who had been a secret agent in France - and stories of sacrifice and loss, told by still grief-stricken survivors who felt - and I sensed this even then - that they had no right to have survived when so many others they knew and loved had not.

Of all these stories I felt most keenly the story of the uncle I never met, my dead uncle. My uncle Pieter had been a promising young actor, with a profile like Rupert Brooke. He joined RAF Bomber Command and was shot down and killed more than a year before I was born. I know the story of his death, how with the pilot dead, Pieter wrestled with the controls and kept the plane flying just long enough for his friends to bale out. His death had touched everyone I knew and he was always spoken of with great affection and pride. But whenever his name came up I remember I always felt excluded because I had never known him and loved him as they had. For me, he was the man in the photo on the mantlepiece by the clock.

He stood there wonderfully handsome in his RAF uniform, looking at me and smiling at the nephew he had never known. His face was frozen in time. It did not age as other faces did. He never died as other relatives and friends later did. He stayed just as he was and he has been like that in my head all my life, forever young. He’s there now as I write. Death and destruction are, of course, the most evident and the most hideous consequences of any war. But there is another more hidden, more insidious result - the fracturing of families, whether though trauma or simple absence. In my own family’s case, my father went off to the war and disappeared from my life, not because he was killed, but because my mother fell for another man while he was away. My mother and father were apparently quite happily married, working together as actors in a repertory company. The war broke them apart, and so my name since the age of two has been Morpurgo, not Bridge, my birth name. The shadow of divorce and separation hung over my mother all her life, and over the family all our lives.

I knew a dear man, a dear friend to me when I was a boy, who happened as a young RAMC orderly to drive into Bergen Belsen in the first convoy of ambulances to get there. What he saw destroyed him. He started drinking to forget and was an alcoholic all his life. He became the central character in my book Billy the Kid.

So with all this there was sown in me a wish to know more, to empathise with how it might have been to live through such terrible times. Maybe I even wanted to be tested as my uncle Pieter was. Who knows? What I do know is that as a writer many of my novels and short stories have been set against a background of war, particularly focused on how war affects those drawn into it, so many of them simply innocent victims of circumstance.

The First World War more than any other is a monument to the futility and the folly of war, its lasting damage for generations to come, and the sheer pity of it. Terrible in its extent in the degree of suffering of those involved and their families, it is a war that haunts us still, in images, in poetry, in novels, a war that should have taught us so much. An early book of mine, Warhorse, was inspired by a picture of British cavalry charging up a hill into barbed wire.

My research took me to my village where I knew there were three octogenarians, all veterans of the First World War, and two of whom were with the cavalry. From them I learnt of the suffering of animals, mostly mules and horses during that war. Two million of them died, that was just on the British side, victims of this manmade massacre, just as the soldiers were.

I wanted to write a story about the universality of the suffering. So Joey, a farmhorse who is sold to the army, tells his story through those he encounters: British cavalry men, Germans who capture him and use him to pull ambulances and then the French farming family who care for him through one terrible winter. It is a tale of loss, but also of redemption.

Both Why the Whales Came and The Butterfly Lion are stories that explore how that war scarred and wrecked lives both in the trenches and back home for generations afterwards.

But it is in my most recent book Private Peaceful that I came as close as I ever have to living the war in the fiction I write. On a visit to Ypres to speak at a conference on writing about war for young people, I discovered that about 300 British and Empire soldiers had been executed, mostly for desertion and cowardice, two for sleeping at their posts.

Courts martial were brief, some less than half an hour. Often soldiers were not legally represented. Vital witnesses were already dead or posted elsewhere. In all 3,000 were condemned to death and 300 were executed. What is clear now is that most of these young men, some still teenagers, were traumatised by their terrible ordeal and in deep shock. I read about a soldier who fought through the Somme. One day in rest camp, he decided that he couldn’t stand the sound of the guns any more and that he was going home. He did not get very far. He was arrested, court martialled and shot six weeks later by a firing squad made up of men of his own company. I saw the telegram sent to his mother to inform her that her son had been shot for cowardice.

I knew already that the British government had recently decided not to acknowledge these injustices, not to pardon these unfortunate men. I felt outraged. It seems to me that a country that does not acknowledge its faults and deal with its shame cannot be called civilised. The New Zealand government pardoned its executed soldiers a couple of years ago.

Private Peaceful follows the lives of two brothers brought up in my village in deepest Devon; farm boys, who find themselves in the trenches enduring the horror and hardships. It is told in the first person by one of the brothers sitting in a barn outside Ypres, waiting for dawn and the execution.

But why write a story on this subject for young people? First of all it is, of course, not for young people at all, but for every one of us, old and young alike. As the night passes and his watch ticks towards dawn, Tommo uses his last hours to look back on his life.

We get to know him well, as a child, as a schoolboy, as a young man going off to war. We see through his eyes his whole world and life, and we empathise with him. If there is one reason for reading a book it is to learn how it is to feel what others feel. This, after all, is the foundation for all human relationships.

Tommo’s life becomes real for us. We share his pain, and through it we grow and learn. Now I hope and believe I understand more about my uncle Pieter, about his last moments as his plane went down. Maybe that’s why I wrote Private Peaceful.

An edited extract from Michael Morpurgo’s Children’s Christmas lecture for the Royal Society of Arts: “From Flanders to the Falklands: stories of children and war”. Private Peaceful is on the shortlist for the Whitbread Children’s Book of the Year award. It is published by Collins Children’s Books pound;10.99