The Missouri Expedition, 1818-1820 : University of Oklahoma Press : 9780806151397 : 0806151390 : 30 Jul 2015 : Repeated clashes between American fur traders and the Plains Indians following the War of 1812 lent urgency to demands that the United States government protect its territory in the West. To remedy the situation, Secretary of War John C. Calhoun planned a military occupation of the upper Mississippi and Missouri River valleys through a cordon of army posts stretching from Green Bay on the Great Lakes west to Montana. Calhoun projected a troop movement, called the Yellowstone Expedition, that grew from one expedition to three&;the Missouri, the Mississippi, and the Scientific Expeditions. The Missouri Expedition, described in this volume, was the first venture to implement Calhoun&;s plan.             During the summer of 1818 the expedition, under the command of Colonel Thomas A. Smith, traveled up the Missouri River in keelboats to Cow Island, near present-day Fort Leavenwort