[Gordis]

Originally Posted by CSteefel

I don't think the WK was hanging behind the other Nazgul, and he was certainly ready to advance when the opponents were much weaker than himself. But he did withdraw on several occasions, the first being the time in the Second Age when Glorfindel drove him off, and then again when Glorfindel drove him off the bridge.

The Witch-King advanced even when the opponents were stronger (like Gandalf) or could present a good challenge (like Earnur, who was the best fighter in Gondor - and note: it was before Glorfindel's prophecy). Frodo as well, as weak as he may have seemed, was not an easy opponent: a nazgul had to have enough guts to attack the wielder of the One Ring. Moreover Frodo had a special blade - for the nazgul he was like a small, deadly poisonous viper.

Indeed, the WK always retreated before Glorfindel, but then again he never sent weaker nazgul to try their hand against the Elf Lord. All the Nine retreated before Glorfindel, because of his special powers in the Unseen, I guess.

Originally Posted by CSteefel

I agree that the attack of the Nine on Weathertop did not involve an all out fight, which as you say may have ended in several participants not surviving, but at least 4 of the Nazgul did follow Gandalf, so I think it was something beyond just driving him off Weathertop.

The reason given in the Hunt for the Ring is this:

Oct. 4: Gandalf repulses the Nazgûl and escapes northwards at Sunrise, and follows the Hoarwell up towards the mountains. [Four Riders] are sent in pursuit (mainly because [the Witch-king] thinks it possible he may know of the whereabouts or course of the Bearer).RC, p. 167-8

There was a possibility that Gandalf would lead them to the Ring.

Originally Posted by CSteefel

Recall also that later Gandalf drove off the Nazgul on the Fields of Pelennor when they chased Faramir and his company. The final faceoff was to come at the Gates of the City, where Peter Jackson has interpreted (incorrectly, IMO) the matchup as turning in the favor of the WK. Another argument would suggest that the WK here again felt himself overmatched, otherwise why not finish Gandalf when he had the chance. I suspect it would have been quite a battle, partly because the WK's power had been augmented by Sauron, but then again Gandalf had apparently been augmented as well with his return

It would have been quite a battle with uncertain result and a good possibility of being fatal for both opponents. I guess the WK felt himself overmatched, but couldn't withdraw because Sauron was watching him. He took the first opportunity to excuse himself. But still, again, he didn't summon the other nazgul to help him.