Smith served in the 1868 Washita Campaign, seeing his first action against the Native Americans. He was promoted to 1st lieutenant on December 5, 1868. He participated in most of the 7th Cavalry's campaigns, including the 1873 Yellowstone campaign and as assistant quartermaster in the 1874 Black Hills expedition. Although the 1st lieutenant of Company A, Smith was named as assigned to command Company E. This was under the command of first lieutenant Charles DeRudio as its nominal commander, Captain Charles S. Ilsley, was permanent aide-de-camp to General John Pope at Fort Leavenworth. These changes were to result in Smith being killed at the Battle of the Little Bighorn and DeRudio surviving.