James Stewart was born around 1836, the son of John D. Stewart. On September 7, 1861, he was mustered into Company I, 12th Iowa Infantry in Dubuque, Iowa, as a corporal. He fought at Fort Donelson in February 1862 and was captured, along with many others from his regiment, at the Battle of Shiloh in April 1862 and imprisoned at Macon, Georgia, until October 1862. Stewart was released in October 1862 and quickly promoted to 4th sergeant, and then 2nd sergeant on October 28, 1862. In July at the Siege of Vicksburg, Stewart was wounded in action. He died December 7, 1863.
From the guide to the James Stewart diary, Stewart, James diary, 1861-1863, (William L. Clements Library, University of Michigan)