Once upon a time in America, journalists wrote “holiday pieces” out of desperation. In a world where amusement parks and beaches beckoned, where businesses carpet-bombed consumers with holiday sales ads, recreation and crass commercialism overmatched the remembrance of important historical persons and events. The “holiday pieces” were rearguard actions, waged to recall Americans to “the reason for the season.” Now, these holiday defenders are even more badly outnumbered. The Left’s culture warriors have supplanted commercials as the chief enemy of public memory. They don’t aim to hijack commemoration days to serve their commercial ends; they aim to erase the meaning...