Answer:
She became invaluable as a guide for the Lewis and Clark expedition, especially in the region of her birth, near the Three Forks of the Missouri, and as a interpreter between the expedition and her tribe when the expedition reached that area. After she gave birth during the expedition to Jean-Baptiste Charbonneau on February 11, 1805, she also quieted the fears of other Native Americans, for no war party traveled with a woman and a small baby. She was able to translate when they met up with Shoshone-speaking Indians. She told them about some of the geography and any various animals and plants that she was familiar with.