 Even when Baum's books experienced a major resurgence in interest and sales in 1918, "The Sea Fairies" sold only 611 copies that year while the Oz books and even Baum's non-Oz works were selling thousands of copies.Once Baum returned to writing Oz books with "The Patchwork Girl of Oz" in 1913, the Trot series was retired – but the main characters lived on.Trot and Cap'n Bill are the main protagonists in "The Scarecrow of Oz" (1915) — the plot of which was reworked from the projected third book in their aborted series – and they play a significant role in "The Magic of Oz" (1919).