I understand the shot struck the steam drum which was located atop the boilers and thus roughly level with the gun deck, hence the large number of casualties among the gun crews when the steam escaped. The unprotected position of the steam drum on the "city-class" gunboats can be seen aboard the partially reconstructed U.S.S. Cairo in Vicksburg National Military Park.

Here in southeast Arkansas it is still widely believed among otherwise well-informed Civil War buffs that the U.S.S. Mound City was sunk at St. Charles. Over the years at least a dozen people have told me that the wreckage of the gunboat is visible during low water. Myths die hard, especially in Deepest Dixie.