From Amazon:

McNamara’s Folly: The Use of Low-IQ Troops in the Vietnam War

by Hamilton Gregory (Author)

In 1966, President Lyndon Johnson and Defense Secretary Robert McNamara were desperate to find additional troops for the Vietnam War, but they feared that they would alienate middle-class voters if they drafted college boys or sent Reservists and National Guardsmen to Vietnam. So, on October 1, 1966, McNamara lowered mental standards and inducted thousands of low-IQ men.

Altogether, 354,000 of these men were taken into the Armed Forces and a large number of them were sent into combat. Many military men, including William Westmoreland, the commanding general in Vietnam, viewed McNamara’s program as a disaster. Because many of the substandard men were incompetent in combat, they endangered not only themselves but their comrades as well. Their death toll was appallingly high.

In addition to low-IQ men, tens of thousands of other substandard troops were inducted, including criminals, misfits, and men with disabilities.

This book tells the story of the men caught up in McNamara’s folly.