This idea first surfaced in the Wooden Leg narrative, but was most fully developed in Keep the Last Bullet for Yourself, considered by Marquis to be his most important work and the culmination of his Custer research.
Adonijah bought a half-share in the newspaper Osceola so that his son, Birney, Marquis' elder brother, could learn the printing trade.
The Standard was the leading newspaper in Montana, financed by Marcus Daly, and built by campaigning editor John Hurst Durston.
In November 1916 Marquis closed his Clyde Park practice and moved to Livingston to share an office with the city health official.
However, Marquis never made professional use of this qualification except for one case where he represented a Methodist minister suing an employer (of a second job) for back wages.
After winning the case, Marquis promptly retired from that career so that he could claim that he was "100 percent successful as a lawyer", but he remained listed as a member of the Montana bar throughout his life.
He then decided to move to Whitehall, where he spent more and more of his time writing, at first on his wartime experiences, and then short articles on diverse subjects collected into volumes.
[21] The cold winters drove Marquis to consider yet another change of career (Whitehall is at an elevation of 4360 ft); he applied to the United States Veteran's Bureau.
In April 1923, he moved to Alberton, where he continued to practice medicine, and published a short story "Buffalo Heart, Indian Policeman", printed in The Youth's Companion, a leading literary magazine.
In June, this success, and the better climate in Alberton, led him to turn down a job offer from the Veteran's Bureau and put most of his effort into work on his Cheyenne book.
Marquis once again applied for a position at the Western Shoshone reservation, but when this was turned down in October he wrote, "rather glad than sorry to hear it", as his writing had progressed a great deal in the interim.
However, Marquis developed a particularly strong relationship with Wooden Leg, whose lengthy narrative eventually became a separate book, A Warrior Who Fought Custer.
Though the man was not named by Marquis, a photograph of him was included in the book, and he was subsequently identified as Sun Bear, a veteran of both the Fetterman Fight and the Custer battle.
[30] In October 1927, Memoirs of a White Crow Indian was accepted for publication by Century, and Marquis was prompted to take down his medical practice sign.
A small success came in December with the publication of "Red Ripe's Squaw" in Century Magazine, it was an abridged version of the Iron Teeth narrative.
However, W. J. Ghent, writing in The New York Times,[34] criticized the claim made by Wooden Leg that many of Custer's men had committed suicide rather than face death at the hands of the Indians.
[39] Marquis' body of work is of value to scholars researching the Plains Indians' way of life in general, especially the Cheyennes, and the Custer fight at Little Bighorn.
[39]His biographer, Thomas D. Weist, agrees, saying that even after his books had gone out of print, "anthropologists, historians, and avid readers of western history continued to seek them out in libraries for their myriad details on the Cheyennes, the Crows, and the Battle of the Little Bighorn.
[41] Liberty says that he is "well trusted generally, as a historian ..."[42] She singles out his final piece of work, the "Custer Battlefield Cheyennes", as being of special interest to American Indian Wars scholars.
[46] In 2003 a new edition of Wooden Leg: A Warrior Who Fought Custer was published with an introduction by Richard Littlebear, Cheyenne writer, educator, and president of Chief Dull Knife College.
[52] The negatives were passed to anthropologist Margot Liberty in 1998 by a remaining project member, Elizabeth Wilson Clark, shortly before her death.
[53] The negatives were sold by Hap Gilliland of the Council for Indian Education to the Buffalo Bill Historical Center museum in Cody, Wyoming.
[54] The theory that Custer's soldiers committed suicide en masse toward the end of the Battle of the Little Bighorn has been controversial from the moment it was first suggested, and the discussion continues.
The notion was so controversial that Marquis could not find a publisher for Keep the Last Bullet for Yourself, his main vehicle for promoting the theory, and the book did not appear in print until 1976, forty years after his death.
Ghent is dismissive of the value of Indians as eyewitnesses: "... he tells what he remembers, along with much that he has imagined ..." and insists that the "body of authenticated fact is in no danger of being disturbed by any new material from any source".
[37] Marquis names a dozen of these in the introduction to the Wooden Leg book, one of whom, Sun Bear, gives a similar account in The Cheyennes of Montana.
[58] Attributing the soldier's suicides to the effects of whisky was a common theory among the Indians, although Wooden Leg believed the prayers of medicine men to have been the cause.
[43] Another suggestion is that the Cheyenne warriors, pressed to recount details of the Custer battle, were still reluctant to admit to killing soldiers for fear of punishment.
Without doubt, the Sioux had the greatest number of participants on the Indian side, but, according to Marquis, they thought they were merely coming to the aid of their allies the Cheyenne.
[72] According to Liberty, the Marquis idea most likely to be disbelieved is his claim that the Northern Cheyennes held a conference with their bitter enemies, the Crows, in July 1875 to discuss territorial borders.