The phrase "those outbreaks of atrocious cruelty so commonly enacted upon the plantation" is evidence that enslaved people were badly treated.
Before the civil war, in the Southern States, the slave labor hand was commonly used to work on the plantations. People reduced to slavery had no rights, nor freedom. Slave labor hand was cheap since workers were not paid, it was part of their service and duties as slaves.
They were treated as objects or animals, that belonged to their masters.
Mistreat and cruel punishments were commonly used on plantations to encourage work.
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