As finally organized, the expedition was made up of the two captains
(Lewis and Clark) and twenty-six men. These were nine young men from
Kentucky, who were used to life on the frontier among Indians; fourteen
soldiers of the United States Army, selected from many who eagerly
volunteered their services; two French voyageurs, or watermen, one of
whom was an interpreter of Indian language, and the other a hunter; and
one black man, a servant of Captain Clark. All these, except the negro
servant, were regularly enlisted as privates in the military service of
the United States during the expedition; and three of them were by the
captains appointed sergeants. In addition to this force, nine voyageurs
and a corporal and six private soldiers were detailed to act as guides
and assistants until the explorers should reach the country of the
Mandan Indians, a region lying around the spot where is now situated
the flourishing city of Bismarck, the capital of North Dakota. It was
expected that if hostile Indians should attack the explorers anywhere
within the limits of the little-known parts through which they were
to make their way, such attacks were more likely to be made below the
Mandan country than elsewhere.

The duties of the explorers were numerous and important. They were to
explore as thoroughly as possible the country through which they were
to pass; making such observations of latitude and longitude as would be
needed when maps of the region should be prepared by the War Department;
observing the trade, commerce, tribal relations, manners and customs,
language, traditions, and monuments, habits and industrial pursuits,
diseases and laws of the Indian nations with whom they might come in
contact; note the floral, mineral, and animal characteristics of the
country, and, above all, to report whatever might be of interest to
citizens who might thereafter be desirous of opening trade relations