Map showing the defenses of the Mississippi and the positions of the mortar- fleet at the opening of the bombardment

Map showing the defenses of the Mississippi and the positions of the mortar- fleet at the opening of the bombardment. The Coast Survey carried triangulation up the Mississippi River which allowed positioning the mortar vessels for indirect artillery fire, one of the first instances of geodesy and survey being used to position artillery (it was done under David Dixon Porter of the Navy)