A disputed 1804 treaty with the Sauk and affiliated tribes led to the U.S. claim of control over western Illinois and parts of what is now Iowa. To establish control, the U.S. Army set out to construct a post near the mouth of the Des Moines River, a major trading route into the interior of Iowa. Not finding suitable land near the mouth of the Des Moines, the expedition also considered land near Quashquame's Sauk and Meskwaki village at the head of the Des Moines Rapids, a choke point of trade and transportation on the Upper Mississippi below modern Montrose. Again, this land was not considered suitable for a fort. The Army settled on a location several miles upstream at what is now the city of Fort Madison.