In 1800, Daniel's first assignment was as a clerk on the "voyageur's highway" from Montreal to Grand Portage, and thence to Fort Alexandria, Saskatchewan. He worked a total of five years in the Swan River Department, as central Saskatchewan was then known, with sojourns (assignments, or tours of duty) at Fort Alexandria, Bird Mountain, and Lac la Pêche.
From 1805 to 1807, Daniel worked on the Saskatchewan River at New Fort, South Branch House, and Cumberland House. On October 10, 1805, he was introduced to the young woman who would become his wife. At the tender age of 14, Lisette was, according to Daniel's journal, "a fair Partner of a mild disposition and even-tempered." Nothing is known of her origin or that of her tribe, and she was long thought to be a Snake Indian from the Kootenays. "Snare" has long been considered a misspelling in Harmon's original journal; recent scholars have speculated that the "Snare" people do exist, and are now the Secwepemec band of the North Thompson River, BC, but in 1997, Secwepemec band leaders were unable to confirm this.