The Lord of the Rings came out in time when the dominating reality was the increasingly real possibility of nuclear war. Of course, Tolkien was not at all thinking of nuclear weapons when he invented the concept of the One Ring and made it a main focus of his epic sequel to The Hobbit; it was certainly not meant allegorically. However, the theme of an overwhelmingly powerful weapon -- and the temptation to use it -- was (in my opinion) particularly applicable to the time when the book was published. Tolkien himself alludes to this in the Foreword to the Second Edition when he talks about how if the book had really been an allegory, than Saruman "would in the confusion and treacheries of the time have found in Mordor the missing links in his own researches into Ringlore, and before long he would have made a Great Ring of his own." As Hammond and Scull write in their Reader's Guide, "the reference is surely to the development of the atomic bomb by the Allies, and to the subsequent proliferation of nuclear weapons to the Soviet Union. Of course the Ring was conceived by Tolkien long before such things came to public attention in 1945."Faramond wrote:Voronwë_the_Faithful:
... It can not be denied that The Lord of the Rings is a timely book; one which (to use Tolkien's word) is tremendously applicable to its time.
And to our time.
I deny it!
How does one apply The Lord of the Rings to a particular time? When I imagine the application of the story to history I see persons with agendas, those who wish to distort history to follow a particular desired narrative, leading to a constructed conclusion. That, I am nearly sure, is not what you imagine; I would like to read how you understand The Lord of the Rings to be applicable to a time in history.
Of course, the temptation of power is a theme that becomes all the more timely as move into the 21st Century. Moreover, the "main theme" of the book - and exploration of death and mortality - is applicable to any time.
Another aspect of 'applicability' that Tolkien refers to in the Foreword is the aspect of the story regarding the destruction of the natural world in the name of "progress". He denies that the Scouring was meant to reflect the situation in England after the war, pointing out that it had been foreseen early in the writing of the book. He goes on to point out that the country that he lived in in childhood was being "stealthily destroyed" before he was ten. It certainly seems clear to me that this theme becomes all the more applicable as time passes (whereas it would not have been applicable to an earlier age).
A couple of little tidbits from Hammond and Scull's LOTR Reader's Companion that I wanted to add. First, apparently the Ring Verse first came to Tolkien when he was in a bath. I never knew that. Secondly, a cute little description of an interaction between Rayner Unwin and Christopher. Originally the statement in the Foreword to the Second Edition that stated the book has been read by many people since finally appeared in print had the words "ten years ago" after "appeared in print". In the next printing in 1969, they changed it "fifteen years ago". After Tolkien's death, Christopher wrote to Rayner on December 27 1976 and said 'I don't think one can go on dating it year by year, can one? -- or we shall end up making my father say "The Lord of the Rings has been read by many people since it finally appeared in print a century ago"!'
There are numerous interesting tidbits that Hammond and Scull point out about the Prologue; too many to point out here, and none that particularly jump out more than the others.
)... so I'll be commenting here if it's not too late to join in 
