Alguns acreditavam que ele fez, mas nunca foi confirmado
Isso é discutido no Apêndice A:
[M]any believed that Denethor, who was subtle in mind and looked further and deeper than other men of his day, had discovered who this stranger Thorongil in truth was, and suspected that he and Mithrandir designed to supplant him.
Return of the King Appendix A "Annals of the Kings and Rulers" I: "The Númenórean Kings" (iv) Gondor and the Heirs of Anárion The Stewards