Final answer:
The name of the group of men who made up the expedition was the Corps of Discovery, led by Meriwether Lewis and William Clark to explore the Louisiana Purchase.
Step-by-step explanation:
The group of men who made up the famous expedition was named the Corps of Discovery. This group was led by Meriwether Lewis and William Clark, who were selected by President Thomas Jefferson to explore the Louisiana Purchase and identify commercial possibilities, map out the territory, discover potential trade routes, and establish relations with native tribes.
The Corps of Discovery faced many hardships, including extreme weather, wildlife, and illness, but despite these challenges, they contributed significantly to the geographical and scientific knowledge of the western United States.