Who is Richard Henry Pratt from The Flight of Red Bird: The Life of Zitkala-Sa and what is their importance?

Richard Henry Pratt was a captain in the United States Army. He believed in taking Native American infants away from their parents in order to send them to boarding schools run by whites. He viewed this practice as a reasonable way to "force" assimilation. Pratt and Gertrude later worked together for Indian rights.