French in Lewis and Clark expedition

George Drouillard, a hunter, trapper, cartographer, and a master of many languages (Indian as well as French and English) was hired by Captain Lewis for the expedition into the newly acquired Louisiana Territory in early 1804. Lewis, who referred to him as "Drewyer," praised him in six elk a day and one day he killed eleven elk[3]. Hunting was the main food supply for the group at the fort since they could not farm and had no trade with the local tribes.

Drouillard was one of the non-military members of the Corps to complete the Lewis and Clark Expedition from Camp Dubois to the Pacific Ocean and back.

http://en.wikipedia.org/wiki/George_Drouillard

as well:

http://en.wikipedia.org/wiki/Toussaint_Charbonneau husband of Sacagawea http://en.wikipedia.org/wiki/Sacagawea#Later_life_and_death

http://en.wikipedia.org/wiki/Pierre_Cruzatte

And Private François Labiche — French fur trader who served as an interpreter and boatman.