McNamara’s Folly: The Denial of Individual Differences”, Gwern2018-05-17 (, , , , ; backlinks; similar)⁠:

Account of well-intentioned but ill-fated attempt to conscript unintelligent or outright mentally-retarded men into fighting in the Vietnam War after remedial education, illustrating the difficulty of social interventions, the practical consequences of low intelligence, and the cruelty & evil of ignoring the reality of individual differences.