If you haven't seen the movie Amazing Grace with Ioan Gruffud (Horatio from the A&E Series Horatio Hornblower), you really should see it. Gruffud plays William Wilberforce, a young British Lord in the 1700's who rises to power and makes it his life's mission to fulfill his uncle's dream of ridding the world of slavery. His uncle, a former slave ship captain, is the same man who wrote the song, Amazing Grace, and later became a minister to try to atone for his sins.
It's a very powerful movie, well acted and inspiring. Definitely worth watching.