The Hudson’s Bay Company’s headquarters was York Factory, on the great bay to which British ships, every summer, brought out supplies for the posts.  The North-West Company followed the route of the old French traders from Lachine by way of the Ottawa or the lakes to the head of Lake Superior, and its principal depot was Fort William on the Kaministiquia River.  The servants of the North-West Company became indefatigable explorers of the territories as far as the Pacific Ocean and arctic seas.  Mr., afterwards Sir, Alexander Mackenzie first followed the river which now bears his name, to the Arctic Ocean, into which it pours its mighty volume of water.  He was also the first to cross the Rocky Mountains and reach the Pacific coast.  Simon Fraser, another employee of the company, discovered, in 1808, the river which still recalls his exploits; and a little later, David Thompson, from whom a river is named, crossed further south and reached Oregon by the Columbia River.  The energetic operations of the North-west Company so seriously affected the business of the Hudson’s Bay Company that in some years the latter declared no dividends.  The rivalry between the two companies reached its highest between 1811 and 1818, when Thomas Douglas, fifth Earl of Selkirk, who was an enthusiastic promoter of colonisation in British North America, obtained from the Hudson’s Bay Company an immense tract of land in the Red River country and made an earnest effort to establish a Scotch settlement at Kildonan.  But his efforts to people Assiniboia—­the Indian name he gave to his wide domain—­were baulked by the opposition of the employees of the North-west Company, who regarded this colonising scheme as fatal to the fur trade.  In the territory conveyed to Lord Selkirk, the Montreal Company had established posts upon every river and lake, while the Hudson’s Bay Company had only one fort of importance, Fort Douglas, within a short distance of the North-west Company’s post of Fort Gibraltar, at the confluence of the Red and Assiniboine Rivers, where the city of Winnipeg now stands.  The quarrel between the Scotch settlers who were under the protection of the Hudson’s Bay Company and the North-westers, chiefly composed of French Canadians and French half-breeds, or Metis culminated in 1816, in the massacre of Governor Semple and twenty-six other persons connected with the new colony by a number of half-breeds.  Two years later, a number of persons who had been arrested for this murder were tried at York in Upper Canada, but the evidence was so conflicting on account of the false swearing on the part of the witnesses that the jury were forced to acquit the accused.  Lord Selkirk died at Pau, in 1820, but not before he had made an attempt to assist his young settlement, almost broken up by the shameful attack of 1816.