The Plains Indian War from 1854 to 1890 was a turbulent period in the United States as settlers and miners invaded tribal lands, claimed rights to the land, and demanded protection from Indian retaliation. In response, the government broke or rewrote treaties, and reservations were eliminated, combined, or reduced, leaving most tribes outside their ancestral homes. The U.S. Army's mission was to move tribes onto the reservations, while tribal elders and members of warrior societies were divided between those seeking peace and those favoring armed defiance, and many family bands evaded the Army or escaped the reservations to continue traditional nomadic life. Conflicts escalated into widespread war, including the Gratten Massacre in Wyoming on August 19, 1854, the Battle of Ash Hollow in Nebraska on September 2, 1855, the Sand Creek Massacre in Colorado on November 29, 1864, the Battle of One Hundred Slain in Wyoming on December 21, 1866, the Battle of Washita River in Oklahoma on November 27, 1868, the Battle of the Powder River in Montana on March 17, 1876, the Battle of the Rosebud in Montana on June 17, 1876, the Battle of the Little Bighorn in Montana on June 25, 1876, the Battle of Slim Buttes in South Dakota on September 9-10, 1876, the Battle of Wolf Mountain in Montana on January 8, 1877, and the Wounded Knee Massacre in South Dakota on December 19, 1890. The Battle of the Rosebud was significant because after their success there, the Cheyenne and Sioux were energized and united and moved to join other tribes in a huge encampment on the Little Bighorn River. General Crook's mission had been to find and capture the Sioux, but the Battle of the Rosebud depleted his Army's provisions, so he returned to Wyoming for rest and resupply. As a result, Crook's soldiers were unavailable eight days later when the 7th Cavalry engaged the same warriors at the Battle of the Little Bighorn. The discovery of gold in the West also drew thousands of people affected by the Civil War westward, first by wagon on the Oregon, California, Santa Fe, Bozeman, and Mormon Trails, and later by rail.