[Diamond18]

If the "bog people" were mostly condemned criminals, it seems odd that Tolkien would consciously use the idea for Elves, Men and Orcs who simply died in battle—more particulary the Elves and Men who were the "good guys". At any rate, I can't recall any mention of where the idea for the Dead Marshes came from, in the "Letters". But I can see the concept working its way into his subconscious and influencing his ideas. It is a very creepy occurance... these bogs and the fact that people were mummified in them. Perhaps the Dead Marshes are so effectively creepy because they actually do resemble something from the real world.