`Patsy, what are you going to be when you grow up? Well?'
'A Royal Engineer, Daddy. A Royal Engineer!'

Charles Drazin knew little about his mother's father - only that he had been a military surveyor who mapped great swathes of the British Empire. But when his mother was told that she was dying, it prompted recollections of her early life that she had never confided before: of the village in the west of Ireland where she had grown up, and of her father, whose death changed the life of an eight-year-old girl for ever.

Soon afterwards her own death left her son to go through alone the relics of her life. They included a box of old photographs, a battered suitcase stamped with the initials of the grandfather he had never known, and the service records of Patrick's brothers, who, like him, had all enlisted in the Royal Engineers as the nineteenth century became the twentieth. So began an extraordinary journey of discovery that took him from the age of Queen Victoria to the battlefields of the Western Front.

Mapping the Past is the story of five brothers who, mapping the world, lived up to the Royal Engineers' motto of Everywhere. It is the story of Ireland, and of the Empire from which it broke away. It is the story of conflict, war and its aftermath. And, most of all, it is the story of memory, endlessly carrying the past, for better or worse, into our present and future. It is an imaginative, intimate and powerful work of history, by a writer of rare power.