Fort Koshkonong was located at a site which today is in the city of Fort Atkinson, Wisconsin, about three blocks east of Main St. along Milwaukee Ave. General Henry Atkinson was the commander of the fort during the Black Hawk War. The fort's location is along the Rock River and is marked with a monument.
Fort Koshkonong shares its name with Lake Koshkonong, which is several miles downriver. That lake is very shallow, and at the time the fort was active, before it was dammed, was actually more of a marsh than a lake.
I may add that Fort Atkinson was constructed of log pickets with loop-holes for musketry, with block-houses on the south-east and north-west corners, with about an acre of ground within the enclosure.
A hand-drawn map of FortKoshkonong dating from 1835 is housed in the Hoard Historical Museum.
The D.A.R. marked the fort's location with a monument in 1907, and a reconstruction of the fort was built in 1966 at Rock River Park in Fort Atkinson.