Europe is marking the centenary of the beginning of World War One, one of the most violent and prolonged struggles of modern history. But European armies not only went to war with each other; they also killed some of their own. The French army executed about 650 soldiers for such things as disobedience and desertion - twice as many as the British army and more than 12 times that of the German military. Now, 100 years on, French families are fighting to restore the honour of their ancestors.
Programme prepared by Elise Duffau and Patrick Lovett