 It is possible but not established that the river obtained its name during this trip.In 1844 he journeyed west on his own, working with brother Nicholas as a scout and interpreter out of Fort Laramie, where he married First Elk Woman of the Oglala Sioux tribe.While returning from a trip to Mexico, he passed through present-day Colorado along the Poudre Valley, arriving at the spot where the Poudre emerges from the foothills.