Congress passed the Indian Appropriations Act of 1851, an early statutory step toward concentrating Native peoples on defined reservation lands by funding federal administration and limiting expenditures outside designated areas—helping formalize the reservation system in practice.
U.S. commissioners and representatives of several Plains nations signed the Fort Laramie Treaty, which recognized broad Indigenous territories while seeking to secure safe passage for overland travel and allow construction of roads and forts—an agreement soon strained by U.S. expansion and enforcement failures.
Colorado volunteer troops attacked a Cheyenne and Arapaho encampment at Sand Creek, killing more than 230 people (many women and children). The massacre profoundly worsened U.S.–Native relations and fed subsequent warfare and intensified pressures toward confinement on reservations.
Congress established the Indian Peace Commission "to establish peace" with certain Plains nations amid escalating warfare. Its negotiations and recommendations helped drive U.S. policy toward reservation concentration and “civilization”/assimilation programs.
At Medicine Lodge Creek, the U.S. concluded treaties with Kiowa, Comanche, Plains Apache, Southern Cheyenne, and Arapaho leaders. The agreements aimed to end conflict by relocating tribes to reservations in Indian Territory and tying peace to federal rations, schools, and agency control.
Beginning in 1869, President Ulysses S. Grant pursued a “Peace Policy” that emphasized placing Native peoples on reservations and assigning (often church-affiliated) agents and schools—linking federal governance, Christianity, and education to assimilation objectives.
The Indian Appropriations Act of 1871 ended formal treaty-making with Native nations, shifting federal–tribal relations toward statutes, executive orders, and agreements and reinforcing unilateral congressional control over Indigenous affairs.
The Carlisle Indian Industrial School formally opened in Pennsylvania as a flagship off-reservation boarding school. It became an influential model for federal assimilation efforts that separated children from their communities to impose English-language instruction and Euro-American cultural norms.
In Ex parte Crow Dog, the U.S. Supreme Court held that federal courts lacked jurisdiction over certain crimes committed by one Native person against another in Indian Country under the applicable legal framework—prompting Congress to expand federal criminal authority soon after.
Federal officials issued "Rules Governing the Court of Indian Offenses" (often associated with the Code of Indian Offenses), establishing Courts of Indian Offenses as an administrative mechanism to suppress certain Indigenous religious and social practices and to enforce assimilation norms on reservations.
Congress enacted the Major Crimes Act, extending federal jurisdiction over enumerated serious offenses committed in Indian Country, including some cases involving Native defendants and victims—significantly reducing the exclusive reach of tribal justice systems.
The Supreme Court upheld the constitutionality of the Major Crimes Act, reinforcing federal authority over criminal matters in Indian Country and supporting a broader legal framework for intensified federal control of reservation life in the late 19th century.
The Dawes (General Allotment) Act authorized the subdivision of reservation lands into individual allotments and enabled the sale of "surplus" lands to non-Native purchasers—centralizing assimilation policy around private property, agriculture, and the break-up of communal landholding.
Reservation System, Assimilation Policies, and the Dawes Act (1851–1887)
