Edward Stanton autograph letter signed, dated 29 June 1865 on "War Department / Washington City" letterhead thanking psychiatrist Dr. John P. Gray and relieving him of duty in connection with the trial of Lincoln assassination conspirators.
Gray had been called in to determine the mental competency of Lewis Payne, aka Lewis Powell, and the other conspirators. Payne's mental health was a central issue in his trial, with his defense mounting an insanity plea based on his bizarre behavior and simplemindedness. Gray did not find Payne to be mentally incompetent and helped the prosecution, which argued that Payne was completely under the control of John Wilkes Booth, secure a conviction. Payne had been assigned the task of assassinating Secretary of State William Seward. Although he managed to attack and stab five members of the Seward household, none of the injuries he inflicted were fatal. Ultimately Payne hung along with co-conspirators Mary Surrat, David Herold and George Atzerodt on 7 July 1865.
The letter, with embossing intact at top left corner, reads: "Dear Sir / Your report on the cases of Payne and other prisoners now on trial before the Military Commission at Washington has been received and is highly satisfactory to this department. In relieving you from the duty it is proper to render to you the cordial thanks of this Department for the ability, industry and fidelity with which you have performed the important duties wherewith you were charged by me, and to express my personal thanks and gratification. I would also request you to return my thanks to your Board for enabling the government to avail itself of your important service. With sincere regard I am Truly your friend / Edwin M. Stanton / Secretary of War".