Uncle Tom's Cabin, the most effective anti-slavery propaganda of the 19th century, opened up with a scene of slaves living in favorable conditions and getting along well with their masters.
A Modest Enquiry Into the Nature of Witchcraft by John Hale is a book credited with ending the Salem Witch trials. In it he acknowledges testimony in the trials that could certainly lead one to believe witchcraft actually happened.
Stowe and Hale acknowledged truth in the opposing side in situations much more oppressive and discriminatory than Trump's border wall or immigration restrictions. People who want to effect change today should take note.