Fort Defiance State Park is a 191-acre recreation area in Emmet County, Iowa, created by the Civilian Conservation Corps during the Great Depression and opened in 1930. Its name preserves the memory of Fort Defiance, built in Estherville in 1862 to protect a gristmill and sawmill during the Dakota War, amid fears that led Iowa to establish frontier forts even though no fighting occurred in the state. The fort arose while many local men were away in Union service during the Civil War. Today the park offers rustic camping, trails, a lodge, and picnic areas, with later improvements supported by local volunteers and students.