On the morning of November 29, 1864, U.S. Volunteer Cavalry launched a surprise attack on a peaceful encampment of Cheyenne and Arapaho along the banks of Big Sandy Creek. Black Kettle, one of several peace chiefs in the village, raised an American flag and a white flag of truce above his tipi, but the attack killed about 200 Cheyenne and Arapaho, many of whom were horribly mutilated. In 1865, the United States Government accepted responsibility for and condemned the massacre as part of the Treaty of the Little Arkansas, but charges were never brought against those responsible. Although permanently affected by the massacre, the Cheyenne and Arapaho hold strongly to their culture, language, and traditions today. In 2000, Congress authorized the Sand Creek Massacre National Historic Site, which preserves approximately 2,400 acres of the massacre site where Cheyenne and Arapaho tribal members still gather to pay homage to ancestors, to heal, and to educate future generations.