Background
The 1862 Dakota War in southern Minnesota resulted in the deaths of 358 American settlers, 77 soldiers, and 36 volunteer militia and armed civilians. Dakota men attacked over 500 white settlers and took hundreds of hostages, mostly women and children, causing thousands to flee. The total number of Dakota casualties is unknown, though 150 Dakota men died in battle. Approximately 2,000 Dakota surrendered or were taken into custody at Fort Snelling, including at least 1,658 non-combatants and those who had opposed the war.
Trials
On September 27, 1862, Colonel Henry Hastings Sibley ordered a military commission to try Dakota men. A year later, the judge advocate general found Sibley lacked authority to convene the trials and had violated Article 65 of the Articles of War, but by then the executions had already taken place. The roughly 400 trials, held between September 28 and November 3, 1862, were conducted without defense attorneys or explanation of proceedings to defendants, some lasting less than five minutes, in an atmosphere of open racist hostility. The commission tried 392 Dakota men and, by November 7, sentenced 307 to death for murder and rape. Sibley confirmed all but four of these sentences.
Presidential review
President Abraham Lincoln reviewed the trial records with two White House lawyers, distinguishing men convicted of participating in massacres from those who fought in battles. Minnesota officials, including General John Pope, Senator Morton S. Wilkinson, and Governor Alexander Ramsey, pressed Lincoln for harsher punishment, warning of "private revenge" if all were not executed. Bishop Henry Benjamin Whipple urged leniency. On December 11, 1862, Lincoln informed the Senate he had ordered 39 executions, commuting the remaining 264 sentences. On December 23, Lincoln suspended the execution of Tatemima (Round Wind) after Sibley raised doubts about his guilt, reducing the number to 38.
Execution and aftermath
On December 26, 1862, the 38 men were hanged simultaneously on a specially built gallows in Mankato, guarded by 2,000 troops due to hostility from the roughly 4,000 spectators. The bodies were buried en masse in a sandbar of the Minnesota River but were exhumed overnight and distributed among doctors for anatomical study, a practice common at the time. Physician William Worrall Mayo obtained the body of Maȟpiya Akan Nažiŋ ("Cut Nose"), dissected it, and kept the cleaned skeleton in his home office. In 1998, the Mayo Clinic returned identifiable remains to a Dakota tribe under the Native American Graves Protection and Repatriation Act and created a scholarship for a Native American student. Separately, Dakota leaders Little Six and Medicine Bottle, who had fled to the Red River Colony, were later captured, tried, and hanged at Fort Snelling in November 1865. A 1912 monument to the hangings was removed in 1971 amid protests; memorial events continue today.