Colonel Charles E. Hooker, Confederate Military History, a library of Confederate States Military History: Volume 12.2, Mississippi
Clement Anselm Evans, Ed.

‘ [18] to call out the volunteer companies of Vicksburg, and take such position as would enable him to prevent any hostile expedition descending the river. On January 10th, Captain Kerr arrived at Vicksburg and—with the Vicksburg Southrons, Capt. L. Moore; the Vicksburg Sharpshooters, Capt. Horace Miller; and the Warren Guards, Captain Brown—proceeded to Fort Hill, above the city, and erected a fort on the bluff. On the next day the steamer O. A. Tyler, from Cincinnati, appeared in the river and, attempting to pass on her way down, was fired on by Captain Kerr. This was the first shot fired during the war on the Mississippi river.’

When it was learned that the forts and arsenals below Vicksburg were in the hands of Louisiana, the military force at Vicksburg was withdrawn and the river was permitted to flow unvexed to the gulf. This action, with the facts distorted and the motives misunderstood, caused great excitement in the Northwest, which seemed to be as ready to go to war for the river as for the Union.