Alan Lloyd was not gung ho about fighting for his country, though his sense of duty was strong.

"I hate flag wagging and Union Jack hurrahing," he wrote to his soon-to-be wife Dorothy, "but I do feel I might be useful." Alan would die in France in 1916, killed by a bomb: "he never had a dog's chance," a friend wrote to Dorothy, now Alan's widow and the mother of a young child. There were thousands of stories just like Alan's and Dorothy's, well recorded in diaries and letters, so one might imagine that writing a "people's" history of the First World War would be easy. When it comes to testimony, the historian is spoiled for choice but that, in it own way, makes the task potentially unmanageable. Isobel Charman has an elegant solution. She focuses on the few to commemorate the many. A handful of people dominate this wonderful book. They are not special or famous but their stories will haunt you for a very long time.

There is, for instance, Reg Evans, a factory worker from Hemel Hempstead. I challenge anyone not to be moved by the letters he sent home. Even in terrible circumstances he was determined to show his mother he was attempting to keep up his religious observances. He reported he had managed to receive Holy Communion at a makeshift service in a public house which, he hoped, "was just as acceptable as if held in a cathedral". Reg behaved with extraordinary valour: crawling across no-man's-land to inspect the damage done to the barbed wire surrounding the German trenches. Sometime later, his war came to a premature end when half his jaw was shot off.

Then there is Kate Parry Frye. The declaration of war provoked "a huge welter of realisation of what we are in for" and she noticed Londoners suddenly stopped smiling: there was "simply a grim, hard and quiet manner". Kate's life would be turned upside down. Her workplace, the Kensington office of the New Constitutional Society For Women's Suffrage, was transformed into a clothing workshop, and she spent the war hovering between pride in her husband's progress through the ranks and fearfulness of the postman's next delivery.

Indeed, the Home Front is a crucial component of this book. It must have been awful to listen to all the rumours from across the Channel, and worse yet to grow accustomed to maimed and disfigured soldiers appearing in your midst. We have the Reverend Andrew Clark to thank for one fascinating glimpse of wartime life in a small Essex village. He kept a diary (92 volumes, and three million words) that recorded everything from the sadness at conscripts being packed off to France to locals complaining about the lack of white bread.

Nothing quite compares with the tragedy of the battlefield, of course. There was the growing sense the war was going to last far longer than expected: Reg Evans quickly realised "old Kitchener knew what he was doing when he enlisted men for three years or the duration of the war".

There was the move from optimism to infuriation. Alan Lloyd resented those who were reluctant to sign up: "all this bleating of married men and shrinking of single men and general unwillingness at home to really take their coats off and get on with it".

And then there was the slaughter. On July 1, 1916 Arthur Burke entered the Battle Of The Somme: "we covered ourselves with glory," he wrote, "but we paid a terrible price." At first there had been a sense of adventure: a colonel declaring "isn't it wonderful," and men shouting "bravo", "good luck", and "cheer-oh". But then "down they fell one by one". There were 57,000 British casualties on that day, a third of whom were killed. By November more than 400,000 British soldiers had been killed or wounded. At no point did the British advance more than six miles into German-held territory.

Charman's great achievement is to let the people who lived through all this speak for themselves. You will be torn between admiration, pity and anger.