Illinois in the War of 1812Russell P. Strange "Book of the Year" Award from the Illinois State Historical Society, 2012. On the eve of the War of 1812, the Illinois Territory was a new land of bright promise. Split off from Indiana Territory in 1809, the new territory ran from the junction of the Ohio and Mississippi rivers north to the U. S. border with Canada, embracing the current states of Illinois, Wisconsin, and a part of Michigan. The extreme southern part of the region