“Colorado in the Civil War,” by John Steinle (Arcadia Publishing) Colorado in the Civil War. By John Steinle. Arcadia Publishing. For a small territory of just 30,000, Colorado contributed an outsized number of volunteers — some 5,000 men — during the Civil War. And they made a significant difference in stopping the war from going west to the California gold and silver mines. At the Battle of Glorieta Pass, Colorado volunteers, led by Maj.