LotR -- Book 5 - Chapter 09 - The Last Debate

[Formendacil]

Tolkien's narrative choice to make the arrival of the black fleet at the Battle of the Pelennor a eucatastrophe is the cause of this chapter. For that reason, half of it really isn't in the movies, not in this position anyway. It's the sort of chapter that would make a killer flashback episode in a television series, especially if you consider that what's going on "at present" (i.e. planning the assault on the Black Gate) is directly tied to what happened "in the past" (Aragorn's march through the Paths and his victories in the South.

"The Last Debate" is very much a high-level view of the plot, looking at the War from Sauron's level more than any other. Arguably, to Sauron, Aragorn's victory at Pelargir was more significant than the Pelennor. This was a supernatural victory and one made by the candidate he most suspects to have the Ring. Meanwhile, the Pelennor--from Sauron's perspective--was more of a mixed bag. Losing his cloud cover AND the Witch-king in one battle is ominous, but it was an acceptable--and temporary--setback once the Rohirrim overthrew Saruman and Aragorn succeeded at Pelargir. And, from Sauron's point of view, it was luck not skill on the part of the West, since Gandalf appears to have been quite ineffective during it. If Gandalf quails to face the Witch-king and Aragorn has the Ring, this is good news for Sauron.