During the thirteen years that intervened between this time and the Civil War, Barnes served in a succession of posts in widely separated parts of the country. He served at Fort Croghan and other posts in Texas, in the plains country at Fort Scott, Fort Leavenworth, and Camp Center (now Fort Riley), on the Pacific coast at San Francisco, Fort Vancouver and the Cascades, while between times he saw tours of duty at Baltimore, Fort McHenry, Philadelphia, and West Point. He was promoted to major and surgeon on August 29, 1856.