Pratt's long and active military career included eight years of service as an army field officer on the western frontier. During that time he participated in some of the signal conflicts with Indians of the southern plains, including the Washita campaign of 1868-1869 and the Red River War of 1874-1875.
He then served as jailor for many of the Indians who surrendered. His experiences led him to dedicate himself to Indian education and from 1879 to 1904, still on active military duty, he directed the Carlisle school, believing that the only way to save Indians from extinction was to remove Indian youth to non-reservation settings and there inculcate in them what he considered civilized ways.
Pratt's memoirs, edited by Robert M. Utley and with a new foreword by David Wallace Adams, offer insight into and understanding of what are now highly controversial turn-of-the-century Indian education policies.