This expedition through the great valley lying between the Rockies on the east and the Sierra Nevada on the west opened up a country unknown except to Indians and trappers, and disproved the idea, which had hitherto been accepted as fact, that a great waterway led directly westward through the Sierra to the Pacific coast. After an excursion to San Francisco the route southward was resumed, along the direction of the coast and about one hundred miles east of it, to a point not far from Los Angeles, then curving up and proceeding due northeasterly and then northerly till Great Salt Lake was again reached at its southern extremity. This great reëntrant curve of three thousand five hundred miles was traveled over in eight months, during the severities of a winter in the mountains and never once out of sight of snow. During these eight months no word had come back to the East from the party, and grave fears were entertained for their safety. The third and last Government expedition set out in the autumn of 1845. The object in view was to follow up the Arkansas River to its source in the Rocky Mountains, to complete the exploration of Great Salt Lake, and to extend the survey westward and southwestward to the Cascades and the Sierra Nevada, in order to ascertain the best route by which to reach the Pacific coast in this lower latitude. Matters were in a very unsettled condition; the Mexican war was impending, and trouble was brooding over our southwestern possessions. Before going on this expedition Frémont was brevetted lieutenant and captain at the same time. [Illustration: Laramie Peak, from one of the old mountain trails.]