Meriwether Lewis and William Clark unveiled many of the mysteries of the uncharted western frontier by leading the Corps of Discovery to the Pacific Ocean and back east in the early 1800s.

And, thanks to the recollections of the arduous trek from their invaluable journals, the third most famous name to endure from the adventure was that of Sacagawea, the Native American teenager who fulfilled a crucial role despite speaking no English and being accompanied by her infant son for the entirety of her 16 months on the journey.

Sacagawea displayed a keen foraging ability and poise under pressure

Born into the Lemhi-Shoshone tribe of modern-day Idaho, Sacagawea had been abducted by the enemy Hidatsa tribe as an adolescent before marrying French Canadian fur trader Toussaint Charbonneau. As such, when Lewis, Clark & Co. established a winter camp near her home in a Hidatsa-Mandan settlement of South Dakota in late 1804, the explorers determined to take along both Charbonneau and his pregnant wife as interpreters.

Sacagawea left the settlement with the rest of the expedition in April 1805, her two-month-old son Jean Baptiste in tow, and quickly proved a useful addition by helping to uncover vegetables and edible roots.

The following month, Charbonneau made a bad impression on his new colleagues when he panicked during a stiff wind and nearly capsized a boat filled with vital documents, instruments, medicine and trading goods. Sacagawea, on the other hand, had the presence of mind to quickly fish many items out of the water, drawing praise from Lewis for her "fortitude."

Her translations ensured supplies and a commitment from the Shoshones

As the expedition slowed to a crawl that summer in the reaches of the upper Missouri River, with little sign of the Shoshone Native Americans they were hoping to contact, Sacagawea provided a boost to the tiring explorers by recognizing landmarks and promising that her people were in the region.

By mid-August, the travelers had finally stumbled upon a Shoshone band which, in an encounter all but scripted by Hollywood, were led by Sacagawea's brother, Chief Cameahwait. The emotional reunion eased most of the lingering suspicions harbored by the natives, and Sacagawea's translations ensured Cameahwait's promise to supply horses, a guide and other supplies for passage through the Bitterroot Mountains.

Still, while Cameahwait's intentions were largely benevolent, he also nearly abandoned the expedition before its safe passage across the mountains to lead his hungry people on a buffalo hunt. Sacagawea caught wind of the plan and told her husband, who eventually relayed it to Lewis in time to hold the chief to his promise during a crucial stretch of the journey.

A painting depicting Sacajawea interpreting Lewis and Clark's intentions to the Chinook Native Americans

A painting depicting Sacajawea interpreting Lewis and Clark's intentions to the Chinook Native Americans

Sacagawea served as a peaceful presence for the well-armed strangers

While Sacagawea had been retained for her ability to communicate with the Shoshones, her involvement provided other benefits for the Northwest natives who didn't know what to make of the heavily armed white men in their midst.

The Umatilla Native Americans, for example, seemed utterly terrified of the uninvited arrivals to their camp in October until noticing Sacagawea and Jean Baptiste. Her appearance, observed Clark, "confirmed those people of our friendly intentions, as no woman ever accompanies a war party of Indians in this quarter."

At the end of their westward march in November, the explorers encountered a group of Clatsop Native Americans who rejected the trade offers for a magnificent sea otter robe. It took Sacagawea's blue bead belt for the Clatsops to hand over the robe, an act repaid by her companions with the gift of a blue cloth coat.

By that point, Sacagawea's value to the mission had been clearly established. Lewis and Clark heeded her wish to join a scouting party headed to examine a beached whale and even allowed her (and Clark's enslaved person, York) to vote with the rest of the group on where to set up shelter for the winter.

She helped guide Clark on the return trip

Sacagawea's legacy as a guide for the expedition is overstated, but she did point the way to Clark on two junctures of the return trip, after the group split for separate paths at the Great Divide, prompting the co-leader to refer to her as his "pilot" through the Montana wilderness.

Furthermore, while it's difficult to quantify, it's likely that the presence of a mother and her baby brought a dose of humanity to an otherwise difficult experience for the participants who constantly pushed through exhaustion, illness and extreme weather. Clark developed a protective bond with Sacagawea, and became especially fond of the boy he nicknamed "Little Pomp," declaring a rock growth off the Yellowstone River to be "Pompy's Tower."

Sacagawea received no direct payment for her contributions

Sacagawea's journey came to an end with her family's return to the Hidatsa-Mandan settlement in August 1806. The sum of $500.33 paid to Charbonneau was for both his and wife's efforts, though Clark soon wrote that she deserved "a greater reward for her attention and services ... than we had in our power to give her."

Sacagawea likely died in December 1812 in Fort Manuel of modern-day South Dakota, with the local clerk calling her "the best woman in the fort" in his public eulogy. 

Fortunately, her memory wasn't to be entirely forgotten. Clark honored his friend by assuming guardianship of Jean Baptiste and his young sister, Lisette, while the surviving stories of the great northwest expedition ensured that Sacagawea eventually took her rightful place as an unlikely hero of American frontier history.