This is Alderney, where the 2,100 people who call the island home do not lock their cars. Where the streets are quiet and the pubs (nine of them) are lively, and the roads don’t have traffic lights. And where reminders of World War II hide behind most corners. A tunnel on Alderney, a British Crown Dependency and part of the Channel Islands, roughly 10 miles from France. The island is at the center of a debate about how to remember Nazi atrocities and live mindfully among sites where misdeeds occurred. This fiercely independent island in the English Channel, roughly 10...