In the beginning of the Progressive era, the attack on knowledge was straightforward. The basic claim was, who needs it? John Dewey sneeringly dismissed academic progress as "mere learning."
Two famous professors, in their 1929 textbook, unapologetically stated that most school material is a waste of time: "Subjects such as arithmetic, language, and history include content that is intrinsically of little value." That clearly reveals an ideology.
But communities sometimes fight back, so the Education Establishment had to be ever creative, ever conniving.
People ignorant of everything, including- maybe especially- history, are much easier to control and lead.