The First World War is known for stagnancy and stalemate—trench-bound days of misery and boredom punctuated by periodic terror and wholesale slaughter.

Soldiers from both sides lived in 2,490 kilometres of trenchworks winding southward from the North Sea through Belgium and France. For them it was a waiting game—a long, cold, mud-soaked ordeal broken only by the call to go “over the top,” a suicidal charge into a hail of bullets, usually at a whistle’s blow...