A Face-palm for Sauron

[Inziladun]

We are all aware that the strategy of Gandalf and the Wise for defeating Sauron was dependant upon Sauron not realizing the Ring still existed and had been found. Gandalf explains it to Frodo:

'And this is the dreadful chance, Frodo. He believed that the One had perished; that the Elves had destroyed it, as should have been done.

I could question just how Gandalf could know Sauron's thoughts on the matter, but I'll let it pass for now.
The problem is, Sauron should have been well aware the Ring was still around.
After all, he was able to re-body after the Last Alliance. The Barad-dûr he was able to rebuild, for its foundations had endured.
One could argue that Sauron had no exact knowledge of what would happen were the Ring to be destoyed, but there is this, when Frodo and Sam stood at the Sammath Naur:

Then his wrath blazed in consuming flame, but his fear rose like a black smoke to choke him. For he knew his deadly peril and the thread upon which his doom now hung.

So it seems he did have an idea what would happen to him upon the destruction of the One.
The Tale of Years says Sauron apparently first arose about the year 1100 of the Third Age and occupied Dol Guldur. Notably very near to the place where Isildur fell and lost the Ring in the Anduin. The Ring was found by Déagol around 2463.
Here's the issue: shouldn't Sauron have realized fairly quickly after he re-bodied that the Ring was still about? If he had, he surely would have discovered much more rapidly what had happened to it, and things would have gone much differently.
Does this make sense, or am I being too hard on the poor, second-rate Morgoth?

[Kuruharan]

I would say Sauron probably wasn't sure himself what would happen if the Ring had been destroyed.

When Frodo was at Sammath Nur it probably suddenly seemed all to likely that the worst might come about. Things often do when bad stuff unexpectedly happens.

I'm not sure we can assume, though, that he wasn't looking for it or at least trying to find out what happened to it from the moment he returned. I think he probably was.

[Eomer of the Rohirrim]

I thought Sauron assumed the Ring had been lost in the Sea: still hanging around, but un-obtainable. So I suppose Gandalf was just havering, more intent on getting Frodo out the door than making accurate guesses in re Sauron's thoughts.

[Boromir88]

Just because you are the maker of something, doesn't mean you know everything about it/how the thing you make will turn out.

I can attempt to make my sister's raspberry coffee cake for the 1st time, and I doubt it will turn out just the same, or just as good, even if I attempt to stick strictly with her "recipe."

When Saruman made his own ring, I doubt he was wanted to have a piece of jewelry for himself, he was trying to mimic Sauron and make his own Ring of power. As far as we know, it failed, and I doubt that was the outcome Saruman was hoping for...

So, simply because Sauron created a powerful Ring, that does not mean he knows everything about it. Sauron had the ability to reform, and re-shape into bodies before creating the Ring, why would his ability to do so after losing it, make him believe the Ring wasn't destroyed?

For as much as we know that Sauron believed no one had the will power to destroy his Ring, people will want to use it against him, maybe he only realized that when he was defeated by Isildur? First he assumes...well guess it was destroyed, too bad. Then after learning that neither the mighty Isildur, nor the stuck-up Elves, wanted to destroy it...that must means none of these weak humans (of the 3rd Age) will want to either. They will only seek to destroy me by using the Ring.

As far as Sauron recognizing his peril when Frodo reached Sammath Naur, that doesn't mean he knew that 2,000 years ago. What Sauron does figure out, is that he was 100% wrong about people not wanting to destroy the Ring. He always assumed the Ring's only threat would be if it was used against him, well if someone's taking it to the place where it can be destroyed, this proves Sauron was wrong, enter in doubt, concern, and fear that he could be wrong about the Ring in other ways too...not only now does someone want to destroy it, but mayber there is a powerful enough will to destroy it! (I'm only theorizing about Sauron's thoughts above, who can say for certain?)

[Inziladun]

Originally Posted by Boromir88

As far as Sauron recognizing his peril when Frodo reached Sammath Naur, that doesn't mean he knew that 2,000 years ago. What Sauron does figure out, is that he was 100% wrong about people not wanting to destroy the Ring. He always assumed the Ring's only threat would be if it was used against him, well if someone's taking it to the place where it can be destroyed, this proves Sauron was wrong, enter in doubt, concern, and fear that he could be wrong about the Ring in other ways too...not only now does someone want to destroy it, but mayber there is a powerful enough will to destroy it! (I'm only theorizing about Sauron's thoughts above, who can say for certain?)

It just doesn't ring true to me that Sauron put such a large portion of his power into the Ring without being fully aware what would happen were it to be destroyed.
The fear he felt when Frodo claimed the Ring so close to where it could be reduced to nothing had to have come from knowing how close he was to permanent disassociation from a corporeal form. What else would he have to fear? He was doing fine without the Ring from a military standpoint. It seems he could have easily won the war had the Ring remained hidden.

[Morsul the Dark]

Oh come on, The Write Brothers made the plane and HOPED it would Fly, Sauron couldn't have known about that, Did it ever get hit and he say Ouch my elbow? It's not something someone assumes. He probably nknew if the ring was destroyed the power he put in it would perish BUT not think He would die...