TYPED LETTER SIGNED (TLS). 1/2 page on a single sheet of letter-size paper, signed "Fritz" in green ink, dated 5 August 1945, to "Dear August" [Derleth]. A businesslike letter to Derleth, as editor of Arkham House, concerning the edition of Leiber's tales that he was preparing. NIGHT'S BLACK AGENTS appeared in 1947, Leiber's first book, and Arkham's 29th. (It was also the first of their titles which went subsequently into a paperback edition, brought out by Ballantine Books in 1961.) In this letter, responding apparently to Derleth's request for blurb material, Leiber refers to a letter he had received from H. P. Lovecraft late in 1936 after sending him the novella, "Adept's Gambit." He points out several sections of the letter, which he had enclosed, that might be suitable for quoting. "... I was delighted to receive a letter from Lovecraft containing not only some general comments, but an unexpected list of detailed criticisms and corrections, which I hastened to make use of in preparing a second writing of the story ... ." The front dust jacket flap did, in fact, wind up using some of this copy. "'Some day I hope the Fafhred Cycle will get into print,' wrote H. P. Lovecraft after reading the manuscript of the novel herewith, 'leading off with Adept's Gambit.'" Bleiler calls NIGHT'S BLACK AGENTS "one of the landmark volumes in modern fantastic fiction" (Bleiler, The Guide to Supernatural Fiction 1002) -- though he didn't care much for the Fafhred/Mouser story, which, in fact, was the only part of NIGHT'S BLACK AGENTS omitted in the Ballantine paperback. The letter links three of the most important figures in mid-twentieth-century American fantastic fiction. Faint fold crease and some mild edge-rumpling, else near fine. (#116646).