The 1st Colorado Cavalry was formed in 1862. Its assignment was to guard the Colorado Territory and its gold mines from possible Confederate invasion, and to protect the ever-expanding white settlements from Indian raids. Troops from the 1st Colorado Cavalry  attacked a party of Cheyenne at Fremont's Orchard in April 1864 and  met the Cheyenne and Arapahoe Indians throughout the spring, summer, and fall of 1864. Traffic on the Platte River trail, one of the main immigration routes into Colorado, came to a halt as the tribes retaliated, and by late summer of 1864 Denver was totally cut off from the east. In September 1864, several chiefs of the Cheyenne and Arapahoe tribes came to Denver for the Camp Weld Meeting, in an attempt to make peace. Territorial Governor John Evans spurned this attempt, and referred the matter to the military commander, Colonel Chivington. Raised in the summer of 1864 in response to Governor Evans' pleas for a regiment of Indian fighters, the 3rd Colorado Cavalry existed for only 100 days. Colonel Chivington was advised to use the "Third" to suppress the Indians before their hundred-day enlistment expired. Thus, the stage was set for the Sand Creek Massacre in November 1864. After attaching another 125 men from the 1st Cavalry, and a section of artillery the 3rd Colorado Cavalry moved in on the only group of Indians Chivington could find --- Black Kettle's camp on the Big Sandy. At dawn on November 29, 1864, they attacked, killing about 150 Indian men, women and children, losing only ten soldiers. About 200 men took part in this episode. This poster was distributed throughout Denver and the surrounding area to rally troops for the 3rd Colorado Cavalry to fight the Indians.