The Fort Atkinson State Preserve in Winneshiek County contains the remnants of a frontier Army post established in northeast Iowa in 1840 by an act of Congress as part of a new Winnebago reservation. It was the only U.S. fort built to protect a native population.Gen. Henry Atkinson was in charge of resettling the native Winnebago tribe on the 40-mile-wide strip of land that was dubbed the Neutral Ground.