Complex sentence: Although another line of the advertisement stated that the book would be ready in August, it was first published by John Lane in the United States in October 1920 and was not published in the UK by The Bodley Head until the following year.
Split into simpler sentences: Although another line of the advert stated that the book would be ready in August. In any event, it was first published by John Lane in the United States in October 1920 and was not published in the UK by The Bodley Head until the following year.