In the early 1960s, Donald A. Wollheim, science fiction editor of the paperback publisher Ace Books, realized that The Lord of the Rings was not protected in the United States under American copyright law because the US hardcover edition had been bound from pages printed in the UK for the British edition. Ace Books proceeded to publish an edition, unauthorized by Tolkien and without compensation to him. Tolkien made this plain to US fans who wrote to him. Grass-roots pressure became so great that Ace books withdrew their edition and made a nominal payment to Tolkien, well below what he might have been due in an appropriate publication. However, this poor beginning was overshadowed when an authorized edition followed from Ballantine Books to tremendous commercial success. By the mid-1960s the books, due to their wide exposure on the American public stage, had become a true cultural phenomenon. The Second Edition of the Lord of the Rings dates from this time — Tolkien undertook various textual revisions to produce a version of the book that would have a valid U.S. copyright.