Increasing numbers of American settlers arriving on the Oregon Trail gave rise to the Oregon boundary dispute. With the signing of the Oregon Treaty in 1846 the U.S.-British boundary was fixed on the 49th parallel. This effectively destroyed the geographical logic of the HBC's Columbia Department, since the lower Columbia River was the core and lifeline of the system. The U.S. soon organized its portion as the Oregon Territory. The administrative headquarters of fur operations, and of the Columbia Department, then shifted to Fort Victoria, which had been founded by James Douglas in 1843 as a fall back position in preparation for the "worst case" scenario settlement of the dispute, in the face of manifest destiny.