Von Scheliha

[SpanishFort]

"In no single instance during the North American war did a naval attack succeed where the channel had been obstructed; and in no single instance did it fail where the channel had remained open," Lt. Col. Victor Von Scheliha, Chief Engineer of the District of the Gulf, "Treatise on Coast Defence," 1868.
Examples of both scenarios are pictured here.

 

[Stryker65]

I would argue that perhaps the battle of St. Charles would be an exception to this idea. The Union naval attack did fail, but because of one lucky shot from the Confederate batteries. The three Confederate ships sunk in the White River were easily brushed away by the Union gunboats, and their attack would have succeeded completely but for the one lucky shot.