[Kuruharan]

Napoleon maintained long supply lines (though at the very end of what was a several thousand mile long line) in both Egypt and in Russia. While he ended up losing both, that was more to his own faults and declining mindset than to the fault of his supply line.

Collapsing supply lines had a lot to do with why Napoleon retreated. But…Age of gunpowder. Incomparable periods of history. Irrelevant.

The Crusaders, a comparable period of time, managed to do much with a combination of stretched supply lines and 'living off the land' tactics.

Except for that irritating fact that the sea was right there and the Crusaders were supplied by sea (and wouldn’t have taken Jerusalem in the first place without it.

The Witch-king had no such option.

Try again.

Ithilien could have been foraged in for some supplies, especially early in the campaign.

Supposing the Witch-king even had access to it. Yet again your theory rests on the utter and complete inertia of Gondor, something I find difficult to believe in.

and I do not think they were quite the same force.

Even if they were not, they must have still had sufficient force to make a powerful effort at rousting the besieging forces.

Hadn't they only decades before faced the Witch-King, who not only caused fear himself but infested the Barrows of Cardolan with evil spirits from Carn-Dum? Should not Gondor have had some sense of what was happening, then?

Not necessarily. And I doubt that the Gondorians had much to do with or heard much about the Barrow-downs. They had other things on their minds when they were there.

and yet not enough for them to come to grips with something they had recently just seen in the Wights

As I said, I doubt they had any contact with them.

And add to that they know about the Nazgul, or at least the Witch-King, and the properties he brings to the table.

I’m not sure how much the Gondorians of that day and age would have known about them. Only the Wise seemed to be deeply versed in the lore and much of the past was forgotten in Gondor as the ages wore on. True, they had just defeated the Witch-king, but I’m not sure that experience would give them a realistic assessment of Nazgûl capabilities. Remember by the time we see the Gondorians talking about the Nazgûl they have had centuries of experience with them.

I certainly think that they would not have been clearly versed in what the Nazgul were capable of doing if they were unclad (which is what my theory rests upon). At some point the Gondorians may have had some inkling about the Nazgul, but what are you supposed to do against an enemy that you can’t see?