In 1864, Curtis returned to Missouri, fighting against the Confederate invasion led by Maj. Gen. Sterling Price. Curtis gathered the forces of his department together, including several regiments of Kansas State Militia, calling his force the Army of the Border. Price's incursion was halted by Curtis' victory at the Battle of Westport. Curtis was then reassigned to a completely different armed conflict, commanding the Army's "Department of the Northwest," which was in the closing phase of a military response to uprisings in southern Minnesota and Dakota Territory by Native Americans against settlers.