Of course, Vonnegut's experience as a POW later served as inspiration for his 1969 novel, Slaughterhouse-Five.
A much-needed transcript follows. Image kindly supplied by Thomas Vance.

Image: Thomas Vance
Transcript
The Atlantic Monthly
August 29, 1949
Dear Mr. Vonnegut:
We have been carrying out our usual summer house-cleaning of the manuscripts on our anxious bench and in the file, and among them I find the three papers which you have shown me as samples of your work. I am sincerely sorry that no one of them seems to us well adapted to for our purpose. Both the account of the bombing of Dresden and your article, "What’s a Fair Price for Golden Eggs?" have drawn commendation although neither one is quite compelling enough for final acceptance.
Our staff continues fully manned so I cannot hold out the hope of an editorial assignment, but I shall be glad to know that you have found a promising opening elsewhere.
Faithfully yours,
(Signed, 'Edward Weeks')