It's well known that Tolkien intended for Lord of the Rings to be a single volume, but the publisher insisted on making it a trilogy because of the practical factors involved in publishing such a mammoth book (such as the price of paper, etc).
Did Tolkien make any changes to his manuscript, after it was decided that it would be published in three parts? Did he move anything around to fit it into one volume vs another, or alter the pacing or the story at all to fit the new structure? Or did they basically just chop it in two places, but otherwise leave it untouched?