This department existed in two separate periods. This department was created on November 9, 1861. It was geographically defined by the state of Missouri, Iowa, Minnesota, Wisconsin, Illinois, Arkansas, and the part of Kentucky west of the Cumberland River. This department was disbanded on March 11, 1862 and combined with the Department of the Mississippi. Commander(s): Henry W. Halleck. The second was created on September 19, 1862. It was geographically defined as the states of Missouri, Arkansas, Kansas and the bordering Indian Territory, and Alton, Illinois. The Colorado and Nebraska territories were added on October 11, 1862. On January 22, 1863, part of eastern Arkansas controlled by Federal forces was removed from this department. On January 1, 1864, the state of Kansas, the territories of Nebraska and Colorado, the Indian Territory, and Fort Smith, Arkansas were transferred to the Department of Kansas. Arkansas was removed from this department to the Department of Arkansas on January 6, 1864. On January 12, 1864, Alton, Illinois was transferred to the Northern Department and then transferred back on February 15, 1864. On May 27, 1864, the department became part of the Military Division of West Mississippi. On January 30, 1865, the Military Division of Missouri was created to include the Departments of Missouri and the Northwest. The Department of Missouri also expanded to include remnants of the Department of Kansas. On February 17, 1865, the department gained the Utah Territory and part of Nebraska Territory. This department was disbanded on May 27, 1865 and became part of the Military Division of the Mississippi. Commander(s): Samuel R. Curtis, John M. Schofield, William S. Rosecrans, Grenville M. Dodge, and John Pope.