The Plains Wars were a series of conflicts between Native American tribes and the United States Army from 1862 to 1890. The wars were sparked by white settlement encroaching on Native lands, breaking of treaties by the U.S. government that reduced reservation sizes, and the Army's lack of understanding of Indian perspectives. Notable conflicts included Little Crow's War in 1862, the Sand Creek Massacre in 1864 where over 160 Cheyenne were killed, and Red Cloud's War from 1866 to 1868 where Red Cloud defeated the Army and forced the closure of forts along the Bozeman Trail. Ultimately, the wars ended with Native Americans losing more of their lands and rights as the U.S. continued westward expansion.