Complex sentence: Preexisting White American belief of Black inferiority informed post-war attitudes and white racial dominance continued to be culturally embedded; whites believed both that Black people were destined for servitude and that they would not work unless physically compelled.
Split into simpler sentences: Preexisting White American belief of Black inferiority informed post-war attitudes and white racial dominance continued to be culturally embedded. Whites believed both that Black people were destined for servitude and that they would not work unless physically compelled.