Undaunted Courage: The Pioneering First Mission to Explore America's Wild Frontier

Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West is a landmark work of historical nonfiction by historian and author Stephen E. Ambrose, first published in 1996. A leading scholar of American military and political history, Ambrose was the author of numerous acclaimed books, including Band of Brothers and D-Day: June 6, 1944. In Undaunted Courage, Ambrose turns his attention to the Lewis and Clark Expedition, presenting it as both a daring feat of exploration and a defining episode in the expansion of the early American republic. This detailed biography of Meriwether Lewis, shaped by his close relationship with President Thomas Jefferson, blends adventure narrative with cultural and political analysis, examining themes of American expansionism, cross-cultural encounters with Indigenous nations, and the personal burdens of leadership.

This guide refers to the 2002 Simon & Schuster paperback reprint.

Content Warning: The source material and guide feature references to graphic violence, racism, including enslavement and anti-Indigenous violence, colonialism, and suicide, along with period-specific terminology and attitudes toward Indigenous/First Nation peoples and enslaved individuals.

Summary

The book opens with Lewis’s upbringing in Virginia and his early career in the military, where he served under William Clark. His appointment as Jefferson’s personal secretary marks a pivotal moment, as the two men develop a close relationship grounded in shared philosophical values and a belief in the importance of westward exploration. Jefferson, envisioning an empire of liberty and commerce after making the Louisiana Purchase, selects Lewis to lead the an expedition he terms the Corps of Discovery, entrusting him with scientific equipment, diplomatic gifts for Indigenous tribes, and a mandate to assert American dominance in the newly acquired territory.

Lewis and his co-captain Clark, along with a carefully selected group of soldiers, frontiersmen, and interpreters (including York, Clark’s enslaved servant), begin their westward trek up the Missouri River. They winter at Fort Mandan in what is now North Dakota, where they receive critical assistance from local Indigenous tribes, especially the Mandan and Hidatsa. Here, Sacagawea, a Shoshone woman married to interpreter Toussaint Charbonneau, joins the expedition. Her presence proves vital, both as a guide and as an interpreter.

After enduring a brutal winter, the expedition proceeds toward the Rocky Mountains. They rely heavily on the knowledge and aid of Indigenous groups, including the Shoshone, who provide guidance and, crucially, horses for the mountain crossing. Despite the explorers’ ambition, the expedition confirms that no all-water route to the Pacific exists, and the Missouri River ends before the Rockies. Crossing the Bitterroot Mountains nearly ends the expedition, and they are only saved by the intervention of the Nez Perce Indigenous people, who provided food and shelter. Finally, they reach the Columbia River and, after navigating its treacherous rapids, arrive at the Pacific Ocean in late 1805. The party builds Fort Clatsop near present-day Astoria, Oregon, where they spend a dismal winter plagued by illness and rain.

The return journey in 1806 is faster but not without peril. Lewis and Clark divide the group to chart additional territory. Lewis, splitting off from Clark for dual missions, explores the Marias River and suffers violent conflict with the Blackfeet, becoming involved in the expedition’s only deadly encounter with Indigenous peoples. Later, Lewis is accidentally shot by one of his own men while hunting. Despite this, both groups reconvene and return to St. Louis, greeted as heroes.

After the expedition, Lewis is appointed governor of the Louisiana Territory, but his administrative work is marred by financial mismanagement, political infighting, and worsening mental health. He delays publishing his expedition journals, begins drinking heavily, and exhibits signs of depression. Ambrose portrays these years as a tragic unraveling of a once-brilliant mind. In 1809, while on the way to Washington to defend himself against accusations of misused funds and to secure reimbursement for government expenses, Lewis dies by suicide at a remote inn in Tennessee.

Ambrose concludes with reflections on the legacy of Lewis and the expedition. While Clark lives a long, productive life, helping to publish the journals and advocate for western expansion, Lewis becomes a forgotten figure for much of the 19th century. It is only in the 20th century, especially after the publication of Reuben Gold Thwaites’s editions of the journals, that Lewis’s reputation is restored.