The Battle of Fort Ridgely was an early battle in the Dakota War of 1862. As the closest U.S. military post to the Lower Sioux Agency, the lightly fortified Fort Ridgely quickly became both a destination for refugees and a target of Dakota warbands after the attack at the Lower Sioux Agency. It came under attack by the Dakota on August 20, 1862, two days after a company of soldiers responding from the fort to the attack on the Lower Sioux Agency had been ambushed and defeated at the Battle of Redwood Ferry. The Dakota besieged and partially destroyed the fort, but were unable to storm it before the August 27 arrival of Colonel Henry Sibley with 1,400 men from Fort Snelling prompted them to retreat.

Nicollet County is a county in the U.S. state of Minnesota. As of the 2020 census, the population was 34,454. Its county seat is St. Peter.