In 1858 Mormon missionaries established Fort Lemhi and began interacting with the Shoshone Indians living in the area. The Mormons established the first irrigation project in Idaho.
Later that year Bannock Indians attacked the Mormons at Fort Lemhi, killing two and driving the remainder back to Utah.
Eventually, the Fort housed U.S. troops and briefly served the defunct Lemhi Indian Reservation.
The Fort Lemhi area was the birthplace of the famous Sacajawea, a Lemhi Shoshone. Today it is the location of the community Tendoy, Idaho.