Familiar with the Headwaters area, Sacajawea became invaluable to Lewis and Clark as an interpreter. In 1800, while camped on the Jefferson River with her Shoshone tribe, she was attacked by a band of Minnetarees, captured, and traded to the Mandans. There, at about age 16, she became one of the wives of the French-Indian trapper Toussaint Charbonneau and accompanied him when he was hired by Lewis and Clark as an interpreter. Sacajawea proved more knowledgeable than her husband, and the expedition came to rely on her. In 1806, Clark wrote that "The indian woman…has been of great service to me as a pilot through this country…"