High Quality Content by WIKIPEDIA articles! Camp Dennison is an unincorporated community just outside Indian Hill in southern Symmes Township, Hamilton County, Ohio, United States. Although it is unincorporated, it has a post office, with the ZIP code of 45111. During the American Civil War, Camp Dennison served as a military recruiting and training post for the United States Army (see Camp Dennison). It is named for William Dennison, the 24th Governor of Ohio and U.S. Postmaster General under President Abraham Lincoln.