In 1861, Chivington recruited and organized the 1st Colorado Infantry. In March 1862, he served in the New Mexico campaign, including the Battle of Glorieta Pass, in which he held the Union command. For his service in New Mexico, he was declared the military commander of the Colorado Territory. In 1863, he became frustrated with his inability to control the warfare between settlers and Indians as troubles in Minnesota and in the Southeast drove the Indians westward. Finally, in October 1864, as a colonel, he ordered an attack on a village of Cheyenne and Arapaho Indians at Sand Creek. The massacre that followed marked the end of his career as a military officer.
