Continuing with my 1999 article in "Michigan History":
LaSalle's route across the Lower Peninsula has fascinated authors and historians for many years. There is, however, only one primary source documenting the trip - a letter LaSalle wrote to one of his investors in September of 1680. The text of the letter has been preserved in Pierre Margray's Memoirs et Documents Pour Servir a L'histoire des Origines Francaises des Pays D'outre-mer; Decouvertes et Etablissments desFrancais dans L'ouest et dans le Sud D'Amerique Septenrionale, published in Paris in the 1880s.
LaSalle clearly understood the difficulty facing him. Reflecting in that letter he explained,
Though the thaws of approaching Spring greatly increased the difficulty of the way, interrupted as it was everywhere by marshes and rivers, to say nothing of the length of the journey. . . and the danger of meeting Indians of four or five nations, through whose country we were to pass, as well as an Iroquois army, which we knew was coming that way; though we must suffer all the time from hunger, sleep on the open ground, often without food; watch by night and march by day, loaded with baggage, such as blanket, clothing, kettle, hatchet, gun, powder, lead and skins to make moccasins; sometimes pushing through thickets, sometimes climbing rocks covered with ice and snow, sometimes wading whole days through marshes when the water was waist-deep or even more, at a season when snow was not entirely melted----though I knew all this, it did not prevent me from resolving to go.
At the time of LaSalle's journey, the southern part of the Lower Peninsula, particularly the area between the Grand River valley and the St.Joseph river valley, was largely deserted. Many local tribes had left the area in fear of the rampaging Iroquois. According to LaSalle, it was a sort of no-man's land. "The Indians do not hunt there because it is situated between five or six tribes which are at war with one another, who, because they fear one another, dare not go to these parts without the greatest precautions; they never appear except with the intention of surprising one another, as secretly as possible."
LaSalle knew he had to travel approximately straight east to reach Lake Erie. He used a magnetic compass to determine direction and an astrolabe, which measures the angle of the sun or North Star above the horizon, to determine latitude. He was unable, however, to determine longitude so he did not know how far it was across the peninsula.
LaSalle was in a hurry. He didn't have time to build or acquire a canoe and take the longer route of going up Lake Michigan to Michilimackinac, then south through Lake Huron, the St. Clair River, Lake St. Clair and the Detroit River to Lake Erie. Going overland through prairies, open oak forests and oak savannas would make for easy traveling, but would leave them exposed to wandering war parties. So LaSalle chose to travel through the Paw Paw River valley. The Paw Paw flows from the east, there were no Indian trails following the river and the southern hardwood forests of the valley made inconspicuous movement possible. The disadvantage was that hiking conditions were atrocious.
NEXT: They are traveling