Fort Ridgely was a US military fort that operated between 1853 and 1867. It was located near the confluence of the Minnesota River and Fort Ridgely Creek, which was inside a Dakota reservation until 1862. To recognize the post’s role in the US–Dakota War of 1862, the state of Minnesota purchased the site in 1895 and established Fort Ridgely State Park in 1911.
Mnisota Wakpa (the Minnesota River) has sustained Dakota people for generations. Dakota relatives gathered at and built burial mounds near its banks for thousands of years. By the mid-nineteenth century, their descendants lived in villages throughout the river’s watershed.
The treaties of Traverse des Sioux and Mendota established a Dakota reservation along the Minnesota River in 1851. White settlers began flooding into the region even before the treaty was ratified, and in 1852, Henry Sibley requested that the US establish a fort on the Minnesota River to suppress potential violence between settlers and the Dakota.
Fort Snelling soldiers began constructing the garrison in February 1853, creating an unwalled collection of buildings encircling a parade ground. Except for the granite barracks and commissary, the fort's structures were made of wood. On June 27, Secretary of War Jefferson Davis named the fort in honor of one of three army officers—all brothers—killed in the Mexican American War. By 1855, construction of the fort’s buildings was mostly complete.
Companies C, K, and E of the Sixth Infantry were the first units garrisoned at Fort Ridgely. Commanding officers and companies rotated frequently; two commanders and one officer brought enslaved African Americans with them. As a result, at least eight enslaved people lived at the garrison during the 1850s.
After the Civil War began, the US used the fort as a training site before sending the soldiers south to fight. By 1862, a company of Minnesota volunteers was garrisoned there.
During the US–Dakota War of 1862, settlers and some Dakota people sought shelter at Fort Ridgely. On August 18, the fort’s commander, Captain John Marsh, attempted to retaliate against Dakota combatants with a force of forty-six of the fort’s seventy-six soldiers. He and many of his men were soon killed in a Dakota ambush.
As the region's main military outpost, Fort Ridgely was stocked with supplies, weapons, and undelivered annuity payments, and was thus a strategic target for Dakota warriors. The Dakota laid siege to the fort, attacking on August 20 and 22. Civilian volunteers, soldiers under the command of Lieut. Timothy Sheehan, and the Renville Rangers (mainly composed of men with Dakota ancestry) defended the fort. After the Dakota retreated, Sibley's militia of over 1,500 volunteers reached the fort on August 27 and 28.
After the war, the US imprisoned around 1,700 non-combatant Dakota people at Fort Snelling. It also executed thirty-eight Dakota men; nullified all treaties and reservations with the Dakota; and exiled most of the Dakota—regardless of their role in the war.
Without the Dakota reservation, the US Army abandoned the fort by 1867, and Congress permitted settlers to purchase lands within the former military reserve by 1870. Homesteaders tore down most of the fort's original structures but left the south wall of the former commissary, which was converted into a stable.
Minnesota began to commemorate the role of Fort Ridgely in the US–Dakota War in 1873, when the state legislature funded construction of a monument for Captain Marsh and his soldiers at the fort’s cemetery. The legislature apportioned additional funds to construct a monument for Eliza Müller, wife of the fort’s doctor (completed 1877), and those killed during the siege of Fort Ridgely (completed 1896).
To further preserve the Fort Ridgely grounds and monuments, in 1895 the legislature purchased five acres of land holding the commissary and building foundations. It directed the Minnesota Adjutant General to care for the neglected state property, and by 1910, the grounds had been cleared and the commissary rehabilitated as a tourist attraction.
The legislature designated Fort Ridgely as a state park in 1911. During the New Deal, the Civilian Conservation Corps (CCC) and Veterans Conservation Corps (VCC) labored there to control erosion and add amenities for visitors. After a 1936 archeological survey, the VCC also reconstructed the commissary to its original appearance.
In 1969, the Minnesota Historical Society (MNHS) took over the fort grounds, with the state retaining control of the wider park. After the National Registry of Historic Places listed the Fort Ridgely historic site in 1970, the commissary building was used as an interpretive center and museum. In the twenty-first century, MNHS partnered with Friends of Fort Ridgely, and later the Nicollet County Historical Society, to administer the park. The latter partnership concluded in 2020.