He was notable for the quality of his hundreds of illustrations for Henry Rowe Schoolcraft's six-volume study on the history of Indian tribes of the United States, commissioned by the U.S.

In 1870, Congress commissioned Eastman to create a series of seventeen paintings of important U.S. forts, to be hung in the meeting rooms of the House Committee on Military Affairs.

A large installation with twenty officers and up to 300 enlisted men, the fort was deep in American Indian territory on the upper Mississippi River.

During that time, he completed some 275 pages of illustrations to accompany Schoolcraft's six-volume Information Regarding the History, Conditions, and Prospects of the Indian Tribes of the United States.

His precise and exquisitely executed illustrations of Indian life, painted almost entirely from his frontier sketches, proved that he was singularly the best-qualified person in the country to undertake this epic work.

[8] Near the end of his career, at the rank of lieutenant colonel, Eastman was commissioned by the House Committee on Military Affairs to paint pictures of seventeen important forts.

One controversial painting was Death Whoop, which was twice removed from display because of negative comments from viewers, as it portrayed an Indian's scalping a white man.

Her youngest son, Charles Eastman, was the first Native American certified as a medical doctor, after earning his degree at Boston University.

After returning to the West, where he served the government as a doctor at the Pine Ridge Reservation, he married Elaine Goodale, a European-American teacher from New England who was superintendent of the Indian schools in the region.

In 1835, while stationed at West Point, Seth Eastman married a second time, to Mary Henderson, daughter of a Southern surgeon and granddaughter of Commodore Thomas Truxton.

The couple had five children together, some born during Eastman's extended assignment in the West when he returned to Fort Snelling for seven years as commanding officer.

Mary Eastman collected traditional stories and legends during their time at Fort Snelling, as preparation for a later book which her husband illustrated.