 The operation had already been canceled and the fleet was in retreat down the river when "Mound City", two of her sisters, three other ironclads, and two tugs were almost trapped at rapids above Alexandria, Louisiana.They were saved only by an impressive engineering feat, the construction of wing dams to raise the water level high enough that the vessels could pass through.The man responsible for building the dams was Lieutenant Colonel Joseph Bailey, whom Admiral Porter credited with saving a fleet worth nearly $2,000,000.