In a letter (#222) to Tevis Clyde Smith, ca. November 1932, Howard writes:

The readers took well to my “Worms of the Earth” story, much to my surprize. I didn’t know how they’d like the copulation touch. My heroes grow more bastardly as the years pass. One of my latest sales concluded with a sexual intercourse instead of the usual slaughter. My sword-wielder grabbed the princess — already considerately stripped by the villing — and smacked her down on the altar of the forgotten gods, while battle and massacre roared outside, and through the dusk the remains of the villing, nailed to the wall by the hero, regarded the pastime sardonically. I don’t know how the readers will like it. I’ll bet some of them will. The average man has a secret desire to be a swaggering, drunken, fighting, raping swashbuckler.

Either the story was heavily censored or most of this sexual action took place in Howard's head. The story is not nearly as sexual as he claims.

Another letter (#226) to Robert H. Barlow, circa December 1932 tells us:

Price tells me that you are interested in the collection of first drafts of Weird stories. I am sending by express, the first writings — or rather the first typings, since I do all my work on the typewriter — of “The Phoenix on the Sword”, “The Scarlet Citadel”, “Black Colossus”, and “Iron Shadows in the Moon”. Some of the pages seem to be missing from the first named story, but the others are complete. Hoping you will find them of interest, I remain,

P.S. “The Phoenix on the Sword” and “The Scarlet Citadel” have appeared in Weird Tales. “Black Colossus” is scheduled for the June issue, and “Iron Shadows in the Moon” has been accepted, but not scheduled.

In a letter (#251) to August Derleth, July 3, 1933, we learn:

You’re probably right about “Black Colossus”. But I find it impossible to write a story about Conan, without making him the dominating character, overshadowing all the others. He simply walks away with it, whether I will or not!

Howard wrote a letter (#343) to Weird Tales circa April 1936 sharing his enthusiasm for the Brundage cover and Vincent Napoli's illustrations for "The Hour of the Dragon":

Enthusiasm impels me to pause from burning spines off cactus for my drouth-bedeviled goats long enough to give three slightly dust-choked cheers for the April cover illustration. The color combination is vivid and attractive, the lady is luscious, and altogether I think it’s the best thing Mrs. Brundage has done since she illustrated my “Black Colossus.” And that’s no depreciation of the covers done between these master-pictures. I must also express my appreciation to Mr. Napoli, who has done a splendid job of illustrating my serial. I hope the readers have liked the yarn as well as I liked writing it.