At Sand Creek on November 29, 1864, U.S. troops attacked Cheyenne Chief Black Kettle's peaceful village, killing several hundred men, women, and children after treaty promises to the Cheyennes and Arapahos had been eroded by the Pikes Peak gold rush and a new reservation boundary along Big Sandy Creek. George Bent, the son of William Bent and Owl Woman, was living with the Cheyennes when the attack came and recalled the panic in the camp, Black Kettle standing before his lodge with a large American flag, and soldiers opening fire from two sides. The massacre opened years of high plains conflict that ended with the tribes' forced removal to lands in Oklahoma, Wyoming, and Montana. In the same broader region, David Butterfield's stagecoach line began running over the Smoky Hill Trail in 1865 as the fastest direct route from Kansas City to Denver, but its isolated stations in Cheyenne country made it dangerous and frequently attacked before Butterfield sold the line to Ben Holladay in 1866. Between 1859 and 1870, stage lines brought thousands of passengers west despite harsh travel conditions and high fares. Later settlement in eastern Colorado coincided with mechanized agriculture, from steam tractors in the late 1800s to gas-driven tractors after 1900, and by 1940 most Colorado farms were fully mechanized. Rural electrification came slowly to these prairies: Hugo built its own plant in 1921, federal aid began in 1936, and this countryside did not receive electricity until 1951.