The Department of the Northwest was an U.S. Army Department created on September 6, 1862, to put down the Sioux uprising in Minnesota. Major General John Pope was made commander of the Department. At the end of the Civil War the Department was redesignated the Department of Dakota.
Immediately upon arriving in St. Paul, General Pope sent letters to the Governors of Iowa and Wisconsin for additional troops to assist the 5th Minnesota Infantry Regiment. From Iowa he received the 27th Iowa Infantry Regiment and from Wisconsin the 25th Wisconsin Infantry Regiment. Both quickly crossed the border to assist with the uprising.[1] The 25th Wisconsin was in Minnesota three months and the 27th Iowa was there a month before both headed south. After they departed, the Minnesota District would be garrisoned by Minnesota units: the 5th, 6th, 7th, 8th, 9th, and 10th Infantry Regiments, the 1st and 2nd Minnesota Cavalry Regiments, plus the Minnesota Independent Cavalry Battalion (Hatch's Battalion) as well as the 3rd Minnesota Light Artillery Battery. In 1864 companies of the 30th Wisconsin Infantry Regiment saw service in the Minnesota and Dakota Districts, too.
From November 17, 1862, the Department was divided into four districts for a short time. The First District was composed of the Iowa and Dakota Territory, the Second was the vicinity of Fort Snelling, the Third was the vicinity of Fort Ripley and the Fourth was the vicinity of Fort Abercrombie. These last three districts were merged into the District of Minnesota on November 23, 1862. The First District remained until June 1, 1863, when the Dakota Territory was merged into the District of Dakota and Iowa into the District of Iowa. Wisconsin was also a District. The Montana Territory was added to the Department on May 26, 1864. The Department of the Northwest, Department of Kansas, and Department of Missouri were combined to form the Division of Missouri on January 30, 1865. On February 17, 1865, the Montana and Dakota Territories west of 110 degrees west longitude were also attached with Major General Pope, who was elevated to commander of the Division.
The Department of the Northwest through the remainder of the Civil War consisted of the Districts of Wisconsin (under Brig. Gen. Thomas A. Davies), Minnesota (Brig. Gen. Henry H. Sibley) and Iowa (Brig. Gen. Alfred Sully). The Department of the Northwest was merged with the Department of the Missouri on June 27, 1865. In 1866 most of the Department of the Northwest was reorganized as the Department of Dakota.
The Department's forces comprised the Sibley and Sully Expeditions of 1863 as well as Sully's Northwest Indian Expeditions of 1864 and 1865. All of these actions were against the Sioux in the Dakota Territory.[2][3]