McNair was assigned to the 4th Regiment of Kentucky infantry, one of several militia groups who moved into this area (Northwest Ohio) in the Fall of 1812. I too have seen the references Micah Taul made about McNair being ordered 12 miles from St. Marys. I ran across one of his letters to the commander at Fort Amanda about 8 miles downstream from McNairs "fort."
Captain David D. McNair and Taul's companies were assigned to Colonel Joshua Barbee's Kentucky regiment. McNair's company was comprised of Cumberland County, Kentucky, residents.
Perhaps McNair's "fort" was built as the result of the following directive (found in the Indiana Historical Collection..):
"Capt. McNair is sent to the last, with directions to build storehouses &. The roads are so extremely bad and the water have been so high as to render it impossible for waggons or horses to travel, not a waggon has arrived at this place for two weeks and but few pack horses & those returning from the advanced posts."