The military played a crucial role in the exploration and settlement of the Freedom's Frontier National Heritage Area region. Expeditions to explore the territory, including Lewis & Clark in 1804-1806 and Pike in 1806-1807, were military expeditions. The military set up posts, Fort Osage in 1808 and Fort Leavenworth in 1827 first among them, to maintain order in the outer U.S. boundaries. As pioneers moved westward through Kansas on the historic trails, so did the military.
As Kansas opened for settlement and tensions flared into the Missouri-Kansas Border War and Civil War, the military again played a big role in the Freedom's Frontier region.