What is the main conflict in Black Beauty by Anna Sewell?

Sewell's intention in writing the book was to promote the humane treatment of horses. Called the "Uncle Tom's Cabin of the Horse," Black Beauty is credited with having the greatest effect on the treatment of animals of any publication in history. The book resulted in legislation protecting horses and a changed public attitude about animal pain and the traditional and fashionable practices that caused suffering for horses. The story focuses on Black Beauty's trials and tribulations under human bondage.