According to the editor, George Rogers Clark’s conquest of Illinois country during the American Revolution, “…was the factor chiefly responsible for giving the Old Northwest to the new-born American nation in the treaty of 1783.” Thanks to Clark, the Great Lakes States are not part of Canada today. If the U.S. had not won the Old Northwest, it seems much less likely that the U.S. would have had the opportunity for the Louisiana Purchase.

Clark’s original memoir is very difficult to read. In this edition the editor of the State Historical Society of Wisconsin, Milo Quaife, rewrote the memoir and added notes to make it more accessible. He also included an Introduction that explains the historical background for Clark’s campaign.