Beginning in the early 1840s the fur trade began to decline as fashion tastes shifted away from beaver pelt hats and the numbers of beavers declined due to over harvesting. Then beginning in the mid-1830s missionaries and settlers began to arrive in the region Also the majority of the Native Americans in many areas were killed off by diseases introduced by Euro-Americans, including up to 70 percent in the Willamette Valley and Lower Columbia valley by 1830. Mass migration began in 1842 when a wagon train of around 100 wagons came overland along the Oregon Trail. In 1846 McLoughlin retired from leading the HBC in the region. Then in 1849 the United States Army arrived after the creation of the Oregon Territory and set up adjacent to Fort Vancouver. In June 1860 the Hudson's Bay Company closed the fort and withdrew to Fort Victoria, essentially ending the systematic fur trade in the region.