I've always wondered if the Allies ever thought of heavily arming & armouring Destroyers or Cruisers, then deliberately beaching them (or at least taking them in very close to shore) to act as forts more or less to support the beach landings.
To me it seems like a good idea (Granted I wouldn't have to man one of those ships, they would become a huge magnet for German fire). You could put allot of bunker busting firepower and armour on a ship.
Was this sort of thing ever considered? Maybe there were heavily armed and armoured small craft or landing craft I am not aware of.
The Germans had artillery and mortars that they could bring to bear on the coast.
This meant that:
Large allied ships stationary near the coast would come under heavy fire.
They would hamper the efforts of the struggling landing craft which would have to navigate around them.
The big cross shaped structures you see in pictures would have prevented any large craft from coming in close enough to hide behind.
Any landing craft staying on the beach would get in the way of others trying to land, and men would just sit behind it. They didn't want the move forwards, the NCOs had a hell of a time motivating them to carry on and not just hide behind any structure. This meant that behind each beached ship would be a great place to land mortar rounds, because of the high numbers of soldiers there.
Naval ships did bombard targets on the coast. But from quite far away. They had to stop by the time the men were going in because of the risk of shrapnel and debris causing friendly fire incidents.
Those are the ones I can think of just off the top of my head.
Consider the problem. The lighter the ship, the closer to shore it can get and provide direct fire support, the closer it is the easier it is to hit.
But the more armor and weapons you put on it the heavier it gets. The heavier it gets it either needs to be a bigger ship/target, or will have a deeper draft.
The deeper the draft the farther out from shore it will run around.
All this for 4/5 beaches that got on relatively fine with off shore fire support. The invasion was not going to fail if Omaha was not pushed through until the next day from other forces moving inland. While you did see destroyers moving to just a few 100 yards off the beach to trade 5in shells with defensive positions.
That being said gunfire support in Normandy in general was pretty perfunctory and not the central effort unlike in the Pacific. There was no desire and some good reasons not to stand off for 3,4,5 days and just go to town on the defenses. Which is what you really need to reduce most prepared positions. The morning bombardments were as much about just keeping the Germans head's down as it was destroying defenses.
Related question: has this technique EVER been used?