When J.R.R. Tolkien originally wrote The Lord of the Rings, he conceived it as one enormous epic. After World War II, there was a huge shortage of paper, and the author's publisher Allen & Unwin was unwilling to commit to producing thousands of copies of a book that length due to the prohibitive costs of the materials required. As a result, it decided to divide the work into three separate releases in order to mitigate its expenditure.
Source：https://www.cbr.com/what-are-two-towers-lord-of-the-rings/
