During the month of August, bands of Santee Sioux attacked settlers and fought the garrison at Fort Ridgely.

The conflict started out when Major Thomas J. Galbraith and Andrew J. Myrick, agents responsible for disbursing food rations to the Santee Indians and otherwise maintaining good relationships with them, refused to give the rations on schedule and insulted the Santee tribal representatives. Out of retaliation, the Mdewkanton band of Santee killed a family of settlers and Myrick. Led by chief Little Crow, the Mdewkanton razed settlements and killed hundreds of white settlers. Surviving settlers fled to Fort Ridgely for protection.

Captain Marsh, commander of the fort, led a group of soldiers to lead settlers to safety. The Mdewkantons ambushed them and half the soldiers were killed, including Marsh. The remaining soldiers fled to the Fort.

Lieutenant Thomas P. Gere led the remaining forces at the fort. Major Galbraith’s company of volunteers, the Renville Rangers, reinforced Gere. Ft. Ridgely lacked a stockade; so most of the defense depended of the skill of Sergeant John Jones, the only artillerist in the whole group of defenders. The first day of battle, Aug. 21, the Santee were held off mostly by grapeshot. A strong thunderstorm rolled in holding off the Sioux a little more. The next day, the Mdewkantons were reinforced by the Sisseton and Wahpeton bands, swelling their force to more than 800. The Santee attempted to set the Fort ablaze with fire arrows, but they were unsuccessful and were driven off by superior firepower. After the Santee were defeated, 38 were captured and hanged in a mass execution