Last Sunday, my cousin, his cousin, their spouses and I arrived by rental car into a small city that until then had existed for us only as a blip on a genealogy chart: Saint-Quentin, in northeast France, where my cousins’ great-uncle Marcel had lived alongside, for a time, their grandfather. We were here thanks to the determined efforts of a history teacher named Damien Bressolles, who since 2023 has been assigning his classes of high school sen…