My 4th great-grandfather was Aaron Mendenhall (1828-1894). In June 1863 he enlisted in the Civil War and mustered out on 02 Sep 1864 at Camp Dennison, Ohio.
Camp Dennison is located just outside of Tymmes Township, Hamilton, Ohio. Surprisingly, it still has people living there- in 2010, the population was 375. During the Civil War, Camp Dennison served as a military recruiting and training post for the United States Army.
To the right is what it looks like today, photos courtesy of Google Maps.