Fort Ridgely played an important role in an armed conflict between the United States and several bands of Dakota, that started when?
Fort Ridgely:  The fort played an important role in the Dakota War of 1862. Dakota War of 1862: The Dakota War of 1862, also known as the Sioux Uprising, Dakota Uprising, the Sioux Outbreak of 1862, the Dakota Conflict, the U.S.–Dakota War of 1862 or Little Crow's War, was an armed conflict between the United States and several bands of Dakota (also known as the eastern 'Sioux'). Dakota War of 1862:  It began on August 17, 1862, along the Minnesota River in southwest Minnesota.
August 17, 1862