False papers - Stewart Ross

It's 1914 and France is at war. 14-year old Pierre is desperate to help his country fight the Germans, but the only way he can sign up is if he has false identity papers. So when the opportunity arises, two years later, Pierre seizes it with both hands and opens the door from childhood into adulthood. But he finds that the world of war is a gruesome one and Pierre's dreams of glory soon fade when he finds out what life is really like in the trenches...

An introduction and epilogue set the story in historical context, and a map provides geographical context.