During the 1820s, yearly purchases of furs rarely exceeded 20 blankets being sold. Increased amounts of animal hides were gathered by Fort Colvile started with the "Flat Head brigade", which joined the Bitterroot Salish on their annual migrations past the Rocky Mountains. A skirmish in 1829 between the Bitterroot Salish and inhabitants of Columbia Lake caused fears among HBC employees about the defenseless state of Fort Colvile Additional employees were sent to erect a palisade and establish the mill during the Winter.