The territory along the Pacific coast lying between California on the south and Alaska on the north--"Oregon," as it was comprehensively called--had been a source of dispute for some time between the United States and Great Britain. After some negotiations both had agreed with Russia to recognize the line of 54° 40' as the southern boundary of the latter's possessions; and Mexico's undisputed possession of California gave an equally well marked southern limit, at the forty-second parallel. All between was in dispute. The British had trading posts at the mouth of the Columbia, which they emphatically asserted to be theirs; we, on the other hand, claimed an absolutely clear title up to the forty-ninth parallel, a couple of hundred miles north of the mouth of the Columbia, and asserted that for all the balance of the territory up to the Russian possessions our title was at any rate better than that of the British. In 1818 a treaty had been made providing for the joint occupation of the territory by the two powers, as neither was willing to give up its claim to the whole, or at the time at all understood the value of the possession, then entirely unpeopled. This treaty of joint occupancy had remained in force ever since. Under it the British had built great trading stations, and used the whole country in the interests of certain fur companies. The Americans, in spite of some vain efforts, were unable to compete with them in this line; but, what was infinitely more important, had begun, even prior to 1840, to establish actual settlers along the banks of the rivers, some missionaries being the first to come in. As long, however, as the territory remained sparsely settled, and the communication with it chiefly by sea, the hold of Great Britain gave promise of being the stronger. But the aspect of affairs was totally changed when in 1842 a huge caravan of over a thousand Americans made the journey overland from the frontiers of Missouri, taking with them their wives and their children, their flocks and herds, carrying their long rifles on their shoulders, and their axes and spades in the great canvas-topped wagons. The next year, two thousand more settlers of the same sort in their turn crossed the vast plains, wound their way among the Rocky Mountains through the pass explored by Fremont, Benton's son-in-law, and after suffering every kind of hardship and danger, and warding off the attacks of hostile Indians, descended the western slope of the great water-shed to join their fellows by the banks of the Columbia. When American settlers were once in actual possession of the disputed territory, it became evident that the period of Great Britain's undisputed sway was over.