The extreme of Russia's pretensions in the matter of extension of territory was reached in 1810, when the subject of the encroachment of American traders was brought again to the attention of our government. Mr. Adams, American Minister at St. Petersburg, in reply to the Russian Minister, suggested that, since it did not appear how far the Russians stretched their claim southward along the coast, it was desirable that some latitude be fixed as the limit, and that it should be advanced as little southward as might be. The answer of Russia was, that the Russian-American Company claimed the whole coast of America on the Pacific, and the adjacent islands, from Bering's Strait southward toward and beyond the mouth of the Columbia River. With this declaration of Russia's claim negotiations were broken off, and were not resumed until September, 1821, when Emperor Alexander issued a ukase, in which he declared all the Northwest Coast of America north of latitude 51° exclusively Russian, and warned all other nations against intrusion within those limits. The extent of the territory claimed in this imperial ukase was less than that of the territory claimed by Russia in 1810, and in particular the extent of the claim was not so great southward. Several events had occurred since 1810 to limit the extent of Russia's claim, though scarcely to modify the imperiousness of her tone. To this intervening period belong the settlement at Astoria of the Pacific Fur Company in 1811, the exploration of the Upper Columbia the same year by David Thompson, an agent of the Northwest Company, with a view to the extension of the posts of his company far to the westward; the purchase two years later by the Northwest Company of the establishment of the Pacific Fur Company at Astoria, and its transfer a few days later to the British flag with the change of name to Fort George; the surrender of the fort in 1818 in accordance with the terms of the treaty of Ghent; the extension westward of the Hudson's Bay Company into this region, and its union in 1821 with its rival, the Northwest Company; and finally the extension over the settlements of the united companies, by an act of parliament in the same year, of the jurisdiction of the courts of Upper Canada. These events had so changed the aspect of affairs on the Columbia at the time of the Russian Emperor's decree in 1821 as to leave him no alternative but to resort to the middle line, and drawing a line midway between the Anglo-American settlement at the mouth of the Columbia and the southernmost Russian settlement to the north of that river, to stand for a southern boundary for his possessions at the fifty-first parallel.