What is the summary of the sand creek massacre

It was the massacre of the Cheyenne and Arapaho peoples by the US army.

Explanation: Leading up to the attack Colorado soldiers began attacking Cheyenne camps without declaration of war. Tribe leaders Lean Bear and Star approached the soldiers to explain their peaceful intent but were promptly shot down. This kicked off the official war. During the attack most tribes stood their ground but in the end many men woman and children were slaughtered by US soldiers. Only a small group of people fled and escaped with their lives. This battle eventually led to the formation of the Little Arkansas Treaty which gave natives free access to lands south of the Arkansas river.

uncle sam would be tossing and turning in his grave : *)