Colonel John Chivington was a Union Army leader during the American Civil War and later led the infamous Sand Creek Massacre against Cheyenne and Arapaho Indians in 1864.
Union Army: The land force that fought for the Northern states, or the Union, during the American Civil War.
Sand Creek Massacre: An event where around 675 U.S. volunteer soldiers attacked a village of about 750 Cheyenne and Arapaho Indians along Sand Creek in southeastern Colorado Territory, killing and mutilating an estimated 70–163 Native Americans.
American Civil War: A civil war in the United States from 1861 to 1865, fought between northern states loyal to the Union and southern states that seceded to form the Confederate States of America.