I believe the answer is: It delayed or extended nationalist struggles.
The nationalist struggles come after different nations started to fully embodied nationalist movement, which make them tend to incline to prove their nation's superiority over another nations. This type of thinking often lead to conflicts among these european nations.
expedition took them up the Missouri River to its headwaters, then on to the Pacific Ocean via the Columbia River, and it may have been influenced by the purported transcontinental journey of Moncacht-Apé by the same route about a century before.
