I think it is clear on reflection to an attentive reader that when his dark times came upon him and he was conscious of being 'wounded by knife sting and tooth and a long burden’ it was not only nightmare memories of past horrors that afflicted him, but also unreasoning self-reproach: he saw himself and all that he [had] done as a broken failure. 'Though I may come to the Shire, it will not seem the same, for I shall not be the same.’ That was actually a temptation out of the Dark, a last flicker of pride: desire to have returned as a 'hero’, not content with being a mere instrument of good. And it was mixed with another temptation, blacker and yet (in a sense) more merited, for however that may be explained, he had not in fact cast away the Ring by a voluntary act: he was tempted to regret its destruction, and still to desire it. 'It is gone for ever, and now all is dark and empty’, he said as he wakened from his sickness in 1420.

Tolkien - Letter 246
(The numbering of letters we often use here refers to how Tolkien's letters are numbered in the collection "The Letters of JRR Tolkien" edited by Humphrey Carpenter. That, BTW is a very interesting read for anyone interested in Tolkien's works and his thoughts. )

....from Two Towers (of herbs and stewed rabbit):

Quote

It does sound pretty autobiographical ( a World War I experience of Tolkien's perhaps?) but also is universal. The passage is all the more effective for being a momentary interlude before Sam is disturbed by the ongoing battle- in particular, the enraged Oliphaunt.
If you imagine drafting it as something Sam says to Frodo (at the time, or " I've been thinking, Mr Frodo..." As they trudge along as captives. ) it doesn't work half so well. Or at least I cant do it (there could be several reasons for that!) but I'm sure Tolkien wouldn't put those words in Sams mouth- Sam speaks more plainly than that.
So, Another thing going on (for me) is the idea that maybe Sam didn't get to think much about the dead man at that moment, what with the Oliphaunt and all; but that the image lodged stubbornly in his consciousness, and replayed a lot over later years. That would chime with what combat vets have told me. The narrator reporting it lets us see the "distilled" version, which Sam might come to over the years.... Then snaps us right back into the moment with the Oliphaunt. I imagine Sam in later years being pressed for exciting War of the Ring tales- but the dead Southron comes to his mind these days more than the Orc he felled with a sturdy thrust of his barrow-blade. And the hobbit youngsters hoping for the dashing stuff you can hear from Mr Pippin after a few ales are doomed to disappointment.

http://newboards.theonering.net/...i?post=602043#602043

I'm not sure he would agree that his depiction of Frodo's alienation at the end of the story was 'shell shock', which is directly associated with heavy combat. The general, more modern, idea of trauma, which we now call PTSD, would be more appropriate, I think. Nor should we too easily transfer our experiences with generally occurring traumas (the list is brutally familiar) to the trauma of losing the One Ring - that is meant to be a mystical or transcendent injury that is not all that common in today's world.