Chiefly official correspondence and general orders relating to Whittle's Civil War service with the 72nd Illinois Volunteer Regiment and with the Army of the Tennessee. His diary (1865) contains descriptions of conditions in Alabama and Georgia during the transition from military to civil law. Also includes court records from cases heard by him as a military judge advocate, biographical sketches, maps, photograph, and other papers. Some letters contain marginalia by Ulysses S. Grant and William T. Sherman.