In the days of slavery, how was suppression openly, scientifically, and consistently applied to the Negro population?

In the days of slavery, the Negros were forced by physical captivity to do what their master commanded. The Negro wasn't allowed to learn how to read or write or even to associate with other Negros on the same premises. Families were torn apart and friends were often separated. The slaveholders in America kept the Negros defenseless, both emotionally and physically.