Fort Ridgely was a US military outpost built in 1853, near the Dakota reservation in southwestern Minnesota.
Yielding to pressure from the US government in 1851, the Eastern Dakota (Eastern Sioux) sold 35 million acres of their land across southern and western Minnesota.
The Dakota moved onto a small reservation along the Minnesota River, stretching from just north of New Ulm to the South Dakota border.
In 1853, the US military started construction on Fort Ridgely, near the southern border of the new reservation and northwest of the German settlement of New Ulm. The fort was designed as a police station to keep peace as settler-colonists poured into the former Dakota lands.
Nine years later, unkept promises by the US government, nefarious practices by fur traders, and crop failure all helped create tensions that erupted into the US-Dakota War in August 1862. Dakota forces attacked the fort twice, on August 20 and August 22. The fort that had been a training base and staging ground for Civil War volunteers suddenly became one of the few military forts west of the Mississippi to withstand a direct assault. Fort Ridgely's 280 military and civilian defenders held out until Army reinforcements ended the siege.
The Army abandoned the fort in 1867. Civilians occupied the remaining buildings and later dismantled them for their own use. From 1935 to 1942 the Veteran Conservation Corps excavated the site, restored the foundations of eight fort buildings, and reconstructed the entire commissary building. In 1970 the fort was added to the National Register of Historic Places, while much of the park was added in 1989. The Minnesota Historical Society assumed stewardship of the site in 1986.