Whenever I’m treading on European soil, there is always a very real chance that the remains of some distant relative might lie underfoot. My family hails from England and Spain, and the history of war on the continent has not spared either branch. This possibility strengthens when visiting places like Thiepval, Vimy, Beaumont-Hamel, or Ypres, four towns—three of them French and the other Belgian—settings of one of the bloodiest wars humanity has ever fought: the First World War, which decimated Europe from 1914 to 1918.

It is now mid-July, and I am visiting northern France. A cloudy day is hiding the summer sun from the region. A few months from now, one hundred years will have passed since the end of