Who is Roger Casement from the novel, Valiant Gentlemen?

Roger Casement is an Irishman who, at the start of the novel, works with the Sanford Exploring Expedition hiring and coordinating porters to carry loads through the Congo. He also writes poetry. Later, Casement becomes a diplomat and humanitarian who seeks to end slavery in Africa. He also travels to South America to record atrocities committed against the native people there.