Pacific Fur Company partner Robert Stuart led a small group of men back east to report to Astor. The group planned to retrace the path followed by the overland expedition back up to the east following the Columbia and Snake rivers. Fear of a Native American attack near Union Pass in Wyoming forced the group further south where they discovered South Pass, a wide and easy pass over the Continental Divide. The party continued east via the Sweetwater River, North Platte River (where they spent the winter of 1812–13) and Platte River to the Missouri River, finally arriving in St. Louis in the spring of 1813. The route they had used appeared to potentially be a practical wagon route, requiring minimal improvements, and Stuart's journals provided a meticulous account of most of the route. Because of the War of 1812 and the lack of U.S. fur trading posts in the Pacific Northwest, most of the route was unused for more than 10 years.