Fort C. F. Smith was a military post established in the Powder River country by the United States Army in Montana Territory on August 12, 1866, during Red Cloud's War. Established by order of Col. Henry B. Carrington, it was one of five forts proposed to protect the Bozeman Trail against the Oglala Lakota (Sioux), who saw the trail as a violation of the 1851 Treaty of Fort Laramie .