Meriwether Lewis and William Clark did not embark on their epic trek across the continent alone-dozens of men and eventually one woman accompanied them. The towering triumph of the Lewis and Clark expedition is due in no small part to the skill and fortitude of such men as Sgt. Charles Floyd, the only expedition member to die; Sgt. Patrick Gass, who lived until 1870, the last surviving member of the expedition; Sgt. Nathaniel Hale Pryor, husband to...