Some links for your consideration:
Matthew Pearl, “K Troop,” Slate 3/4/16
“Little War on the Prairie,” audio episode of This American Life, 11/23/2012 about the 1862-1863 Dakota War
Pamphlet history on The Army and Reconstruction, 1865-1877 (Army Center of Military History)
Little Bighorn National Monument (National Park Service)
Wounded Knee Massacre (1890) Primary Source Set from Digital Public Library of America