One tragic example: Extreme dehumanizing language was a strong contributor to the 1994 genocide in Rwanda. As I have written, the Hutu majority used a popular radio station to continually refer to Tutsi tribal members, a minority in Rwanda, as “cockroaches.”
As support for this characterization grew among Hutus, it essentially stripped away any moral obligation to see Tutsis as fellow humans. They were just vermin that needed to be eradicated.