By the fall of 1804, Sacagawea was expecting her first child. But that didn’t prevent Charbonneau, a wanderer by nature, from asking Lewis and Clark if they would hire him as an interpreter.
He knew Hidatsa and the sign language common among the river tribes. Lewis and Clark enlisted him right away. When they found out he was married to a Shoshone, they encouraged him to bring her along. They had heard that the Shoshone had fine horses, which they would need later. They figured the presence of Sacagawea would make the Shoshone more open to negotiations, and any Indians they encountered would view them as peaceful since war parties never included women.