I just don’t see that interpretation in the text. Merry’s blade broke the spell that held the Witch-king together, killing him. Not Eowyn’s sword-thrust. All that did was to destroy her sword, and seriously numb her sword-arm.
But it seems he COULD have safely ignored the Ents, but for a pair of hobbits that dropped into their midst to stir them to action. (Which he was responsible for transporting in, but how could he know THAT?)
And let’s say for argument’s sake that Ugluk and Co. arrived at the falls, say, 2 hours earlier, and managed to catch Frodo along with the other remaining 8 companions. Then with the Ring in hand, Saruman would probably have come out the big winner - or at least, had as good a shot as he ever would at being the big winner. Sauron would not just roll over, and apparently had a plan as to how to take the Ring back from Saruman if he tried to keep it for himself, based on what Pippin was forced to say: “This dainty is NOT for him… I shall send for it at once! Do you hear me? Say just that!”
Based on what happened after the Palantir Incident, though, that plan was apparently to send over one lesser (not Chief) Ringwraith to say “fork it over, dude”, and who could be daunted by a Ringless Saruman saying “piss off, I ain’t got it” into going away “as one full answered” - and who also pointed out that if he HAD had the Ring, “You would be bowing and calling me Lord”.
Meanwhile, why does Saruman come so close to getting the Ring? He also found out it was in “The Shire” from Gollum, long before Aragorn finds out from Gollum that Sauron had got to him. Quite a head start. Then, Aragorn tells Gandalf, who goes to test Bilbo’s ring and to tell Frodo of his peril, then tells him to stay put and not leave too suddenly.
That’s MONTHS of lead time. What happens in all that time? Well, eventually, just as Frodo is moving to Crickhollow after a full summer passes by, a few Nazgul show up to look for “Baggins”. I can’t believe that Sauron, after 2,000 years of recovery, would spend that time playing Tiddlywinks. No, I’m sure he handed it off to his Nazgul as their Top Assignment… Who THEN spent a few months finishing their Rotisserie Orcball League or something before getting on their black horses and riding to the Shire.
Once there, these Nazgul are within feet of the Ring several times - right at the ford of the Brandywine River, not to mention on Weathertop - but pull back due to some water and a man waving a torch (Heir of Isildur notwithstanding, being “of a ragged line long bereft of lordship”, as judged by one who would know).
So, the biggest wussbags as measured against the badassery they SHOULD be: 9x Ringwraiths.
I think it still took a final blow after Merry’s sword unknit the spells. No matter what,it was Éowyn’s blow killing the Foul Beast that brought the Witch-King down to striking range of Merry.
I am more than fair about suspending my disbelief in stories but when watching the film I actually shouted at the screen at this point: “Aren’t you going to need that army???” What a douche.
I dunno. I can buy that the specific thing the Dead Men agreed to do was to save Minas Tirith from being overrun in the Battle of Pelennor Fields; trying to force them to do more would have been unwise and more likely to backfire than not. Gandalf didn’t try to order the Ents to lend a hand either.
I’m also not sure you want to take an army of treacherous, resentful spirits toward Middle-Earth’s greatest living sorcerer.
I think perhaps in this context “slippery slope” should be read as “water slide”. 
Indeed. The keyword here is “Necromancer”.
Abso-freakin’-lutely. Woe unto the guy in myth, fairytale or legend who imposes just a bit too much on undead spirits with the means and opportunity of getting back at him.
To be fair, the ghost army never reached Pelennor Fields in the book. They used it to drive the Corsairs away from their ships and ‘borrowed’ their fleet. The army which Aragorn took with him were the remnants of the Rangers, Gondorian folks who joined up and freed slaves.
I really wish Peter Jackson have just followed the book for this plot arc.
Besides, as others have pointed out, worse may happen if Aragorn breaks his oath towards the Dead.
The bolded bit was necessary why? 
snarf 
Using the ghost army at the Pelennor Fields simplified that part of the story… and I can see why PJ chose to go that way…
(Although I feel it diminished the sacrifice of the Rohirrim and other men of the west to have the ghost army overwhelm Sauron’s forces so handily).
…some other PJ changes – especially in TTT – not so much.
I despise Jackson’s version of Return of the King, but I can actually understand why he changed it thus. Otherwise he’d have to explain the Rangers who came to join the Three Hunters on their trek from Rohan to Gondor, and then the Corsairs, and…
well, kit gets complicated.
Movie still sucks, of course. 'Cept for Sam versus Shelob and of course anything with Eowyn.
:: ritually spits on that bastard movie-Aragorn who led Eowyn on and broke her heart, just like a Welshman ::
We probably shouldn’t derail this honorable thread with a discussion about Mr. Jackson’s movies, but I also very much like the sequence where the Ered Nimrais beacons are lit. (I exclude the movie’s version of Pippin’s roll in same.)
But I’d also like to offer Manwë’s competence up for discussion. His ability to lead, well, anything, seems highly suspect. He’s the figurehead ruler who apparently never actually does anything useful himself except pontificate from time to time and preside over festivals on occasion.
If we were on the first or second page I’d agree that the Jackson movies should be off limits, but we’re on the third or fourth. Plus I’m the OP. So talk away if y’all want.
(I’ll even concede that Fellowship was the best movie of the last decade and the third-best fantasy movie ever made.)
I also think Manwë is hugely incompetent. He’s like a reverse Cobra Commander, he is. You gotta think that both Ulmo and Tulkas had dark thoughts about kicking his idiot ass off the mountain and were only restrained by their better natures.
How hard is two extra lines of dialogue:
“I have a few Ranger friends who will be joining us…”
“The Corsairs have sided with Sauron and are coming up the river…”
These explanations don’t have to be detailed.
I’ll go with the Orc who led the attack on Helm’s Deep. Even with the tremendous orcpower advantage, he couldn’t fully break into the fort. Then when they finally get them to come out, they get destroyed when Gandalf and a few horsemen show up. Hello Orcs…ever hear of forming into squares to prevent cavalry attacks like Wellington at Waterloo? Get blinded by a few beams of sunlight? You make the Roman commanders at Cannae look good.
Well in the Orc Captain’s defense, it was what 5000-6000 years before those notable occurrences. Also as an Orc he was, well to be nice, stupid and over-confidant by birth.
A bit of a hijack, but I often muse about how I would have scripted and shot the whole Dead + Corsairs + Aragorn to the Rescue scenes of the movies, if I were directing and following the book. 'twould be difficult (and depend heavily on flashbacks.)
The Dead probably wouldn’t even have been useful at the Pelennor Fields, anyway. In their victory over the corsairs, it wasn’t even clear if their weapons would have done anything at all, since the enemy all fled at the sight of them: Fear was a potent enough weapon for them to wield. But when you’re up against an army that’s led by wraiths, well, that might not work so well.
I hadn’t thought of that, but you’re entirely right.
Or possibly wight.