The 9th Indiana Volunteer Infantry Regiment was a volunteer infantry regiment in the Union Army during the American Civil War. It was organized on April 22, 1861, for three-months' service in Indianapolis. After being reorganized for three years' service in late August and early September 1861, the 9th took part in many major battles, including Shiloh, Stones River, Chickamauga, Lookout Mountain, Missionary Ridge, Kennesaw Mountain and the Siege of Atlanta.