Final answer:
There is no specific record of a 'secret message' regarding Native Americans sent back to Jefferson by Lewis and Clark. The expedition focused on mapping the Louisiana Territory, exploring natural resources, and establishing relations with Native American tribes, recognizing the inevitability of expansion and its impacts on indigenous populations.
Step-by-step explanation:
The Lewis and Clark Expedition, authorized by President Thomas Jefferson, was tasked with exploring the newly acquired Louisiana Territory. Jefferson's objectives were multifaceted; he sought the discovery of an all-water route to the Pacific Ocean, to map the territory, to catalogue its natural resources, and importantly, to establish relations with Native American tribes.
On the topic of a secret message regarding the Native Americans, the historical record does not indicate a particular 'secret message' sent back to Jefferson. However, the expedition did aim to assert American sovereignty in the region and facilitate future peaceful interactions and trade with Native Americans, while also recognizing the potential for resistance and eventual displacement of some tribes due to expansion.
The expedition made significant strides in achieving Jefferson's goals. It traveled from the Mississippi River to the Pacific Ocean, though it failed to find the non-existent Northwest Passage. Along the way, they mapped the territory, identified new flora and fauna, and initiated diplomatic relations with various Native American tribes. This ultimately made the territory more known to Americans and supported U.S. claims to the region.