James Isaac Christiancy was born around 1844 in Monroe County, Michigan, to Isaac and Elizabeth Christiancy. His father was a lawyer who owned $8,000 of real estate. He grew up and attended school in Monroe, Michigan, and he enrolled at the University of Michigan in 1861.
He left college after a year, and he enlisted in the Union army on May 28, 1862. He mustered in as a private in Company C of the 17th Michigan Infantry on July 2. The regiment took part in the Battle of Antietam. He was promoted to sergeant major on August 26, 1862. Then, in November 1862, he was promoted to 2nd lieutenant in Company D of the 9th Michigan Cavalry. He served as an aide to General George Custer. He took part in the Overland Campaign, and he was wounded in the Battle of Haw’s Shop on May 28, 1864. He mustered out on August 22, 1865.
He returned to Michigan after the war, and he spent another year at the University of Michigan. He moved to Washington, D.C., in the 1870s, and he worked as a clerk in the Bureau of Pensions. He married Edith Phillips in July 1889, and they had at least one child. In October 1892, he received the Medal of Honor for his actions at Haw’s Shop. He died on December 18, 1899.