The teaching of history has become a flashpoint in the culture wars. But while the battle is fierce, it’s not new. An earlier round in the conflict in the 1920s — over the teaching of the American Revolution — indicates that it will be crucial for historians to weigh in loudly and forcefully during the current debate. That will give them the space to continue to teach the most accurate, up-to-date version of U.S. History and prevent forces that fundamentally don’t understand the job of historians from shaping what American children learn about the past. In the late 19th century,...