Answer:
They agreed with Douglass on the condemnation of slavery.
Explanation:
Frederick Douglass was an excellent orator, he could express himself well, in addition to living the harmful effects of slavery, he could use his experiences to convince people that the slavery system was cruel and insane, and that slaves were people who were born free and who did not deserve this kind of treatment. Before such a great orator, it was difficult for anyone not to agree with Douglas's thoughts, so his white colleagues, after hearing him speak, began to condemn slavery.