In historical writing, the introduction of an essay, article, or book operates as the roadmap for the work. It’s tells the reader exactly what the goal, objective, or argument of the work is, lays out its periodization, and it’s major themes.
Adina Back’s introduction in “Exposing the ‘Whole Myth” of Segregation,” she opens with a vignette, which she analyzes and then connect her analysis to the major argument and themes of her essay. Thereafter, she frames her essay within the context of what others have written and proceeds to develop what she will do in the essay.