Complex sentence: Because of his position as member of a slave owning family, Sanchez identitfied with the anti-abolitionist cause that evolved into one of white-supremacy during post Haitian Revolution period in the Americas.
Split into simpler sentences: Because of his position as member of a slave owning family, Sanchez identitfied with the anti-abolitionist cause. His vision of the his side of the cause evolved into one of white-supremacy during post Haitian Revolution period in the Americas.