On Twelfth Night, members of the Garden District Citizens Command Post gathered to plot their strategy for Carnival. Laminated signs had been printed. A port-a-potty had been rented. Last year, the cleaning crews on Ash Wednesday picked up the white tent that houses HQ, but a replacement had been bought. They were ready for operations at the pocket park on Toledano Street. Only one important matter had to be decided: what would they eat?

It began five years a...