Well, Kransha has put the case well in his 'hagiography' of Denethor, but i can't let it stand, lest others be seduced
I have to say that while Denethor seems, as Tolkien says, more than capable of reading men's hearts, he is incapable of reading his own. He is simply unable to accept that anyone else could rule better than himself (or perhaps he simply doesn't care whether anyone else could - he has the rule & that's it. What he forgets (or chooses to ignore) is that he is
not King. He swears an oath to rule till the King comes back, but plays around with the the letter of the law till he convinces himself that that possibility can never happen.
It seems he values the letter of an oath rather than its spirit. Oathbreaking is to be punished with 'vengeance' - yet how does Denethor understand the nature of an oath?
As ruler he has an obligation to put the good of the realm & people first - 'The rule of Gondor is
mine & no other man's[/i]' - this is a meaningless statement of simple fact: it adds nothing, it is simply saying 'I'm in charge!'
Denethor, unfortunately, has identified himself with Gondor - he
is Gondor in his own mind - he sees no difference between himself & the realm, so that if he falls Gondor falls, if he surrenders - to Sauron or to Aragorn - Gondor surrenders. In short he has identified himself with his role & lost his humanity in the process. What we see in his final moments is a whining coward, or a lost child, perhaps, crying over the loss of his 'son' who probably symbolises for him his 'house' - his rule, his power. What he has doen to Faramir is what he has done to his realm - thrown it away in his madness & he is now crying over the milk he has spilt, & has decided he will trash the house because he can't get it back into the bottle.
He is (was) a competent tactician, but his motivation was saving his own power base, not the good of his people.
[|QUOTE] So do all great lords, if they are wise, Master Halfling. Or why should I sit here in my tower and think, and watch, and wait, spending even my sons? For I can still wield a brand."[/QUOTE]
No they don't - no 'Great Lord' does that - Theoden may have done it with Theodred, but he was old & broken when he did so - Denethor is neither. How can he possibly justify 'spending his sons' when he can 'still wield a brand'? Whatever that is, it is not 'wise', it is callous. And to speak (to even be able to
think of his sons as something that can be 'spent', shows how far he has fallen.
He fears his 'body will grow timid' - why - only because his mind & heart have already. He is like the First World War generals, sitting safely in their war rooms, miles from the front, 'spending' their country's 'sons'.
Of course there are reasons for his behaviour & choices, but not good ones. We can see his character developing all through his life into what it becomes at the last. Basically, Denethor is incapable of doing anything but rule others - a steward should be a servant, but Denethor has never, it seems, considered himself a 'steward'. He doesn't have the right or the authority to reject Aragorn's claims out of hand - which is what he does, because he asks no-one's advice in the matter - no his councellors, his allies, or even his surviving son's. He acts like he is King, but he isn't. In a sense, his desire for the Ring has overwhelmed him - but that's because it was already in his nature to be overwhelmed by it. Its interesting to see that someone can be taken over by the Ring without even having seen it - because the 'Ring' is not just the physical object itself, its more, its desire for power & control.