The event you write about took place on November 29, 1864. This Massacre is also called the Battle of Sand Creek, or the Chivington Massacre. What happened T. was that Colorado Militia troops attacked an encampment of Cheyenne and Arapaho American Indians, about 120 miles southeast of Denver.he event you write about took place on November 29, 1864. This Massacre is also called the Battle of Sand Creek, or the Chivington Massacre. What happened T. was that Colorado Militia troops attacked an encampment of Cheyenne and Arapaho American Indians, about 120 miles southeast of Denver.