David Thompson was the first European to navigate the full length of the Columbia River. Between Kettle Falls (3 July 1811) and the Junction of the Columbia and Snake Rivers (9 July) he was travelling through country that had never been visited by Europeans, and took time to visit the villages along the way to establish good relations, helped by copious quantities of tobacco. In 1805 Lewis and Clark had descended the Snake River, and then continued down the Columbia. On reaching the junction Thompson erected a pole and a notice claiming the country for Great Britain and stating the intention of the North West Company to build a trading post at the site. This notice was found later that year by Astor company workers looking to establish an inland fur post, contributing to their selection of a more northerly site at Fort Okanogan. The North West Company established its post of Fort Nez Percés near the Snake River confluence several years later. Continuing down the Columbia, Thompson passed over the Celilo Falls, almost losing the canoe on the rocks, and portaged around the rapids of The Dalles and the Cascades Rapids. On 14 July 1811, Thompson reached the partially constructed Fort Astoria at the mouth of the Columbia, arriving two months after the Pacific Fur Company's ship, the "Tonquin".