Mustered into the Union Army by companies at Fort Snelling, Minnesota, between October 2nd and November 14th 1861, the 3rd Minnesota was sent to Kentucky. There the unit was placed on garrison duty in Kentucky and Tennessee. Must of the men of the 3rd were taken prisoner July 13th 1862 by Confederate General Nathan Bedford Forrest at Murfreesboro, Tennessee. The men were paroled and sent to Benton Barracks in St Louis, Missouri to wait for exchange. The official exchange took place August 27th 1862, and the 3rd was transferred back to Minnesota. In it’s home state the men were used to suppress the September 1862 Dakota War.The 3rd was reorganized at Fort Snelling following the Dakota War, and they returned in January 1863 to garrison duty in Kentucky and Tennessee. They were called to join the Siege of Vicksburg, and they participated in the capture of Little Rock, Arkansas on September 10th 1863. The 3rd would remain in the city on garrison duty until April 28th 1864. The 3rd took part in an expedition up the White River in Arkansas, which ended in the Battle of Fitzhugh’s Woods April 1st 1864.
The 3rd was discharged from military duty September 16th 1865 at Fort Snelling, Minnesota. They lost 17 men who died in battle or of their wounds. They also saw 279 soldiers die from disease.