How did african americans like frederick douglass and sojourner truth combat slavery?

Work to rule is the most effective resistance to "the man".
Work to rule is a process where the worker does exactly what he is told to do, no more no less. Instructions are never are complete enough to do a task properly so tasks can be done wrong enough to be useless. At the same time the worker can say that he did just what he was told to do so no punishment is merited.