I would be interested in the films makers evidence that this is so...But the West India Regiments service in West Africa was the Ashanti wars...Native Africans (mostly Fante) were part of these regiments.

Many of these regiment would have come across slave ships on their way to Central America...Maybe it was not so much seeking revenge but stopping the slave trade that inspired them.

Although William Gordons medal[1892-post 1888] was shamefully earned, putting down an African rebellion