Letters to his wife, Mary Soule, written while serving as an officer in the Union Army during the Civil War; Civil War diary, 1863-1865; a letter from Byron Stoddard of the Sixth Michigan Infantry; correspondence, 1890-1904, with J. C. Leonard who collected materials for University of Michigan Museums throughout the western part of the United States; literary manuscript of Annah May Soule; and photographs.
Portraits and photographs of Soule and his wife, Maryy Soule; group photograph of the officers of Company D, Sixth Michigan Infantry, 1861; and album, ca. 1865, of Civil War soldiers, most of whom were members of the Sixth Michigan Infantry.