May 31, 1943
My dear Doctor Soper:
Since the plans of the International Health Division of The Rockefeller Foundation for investigations of typhus fever in North Africa have reached the stage at which the Foundation desires your transfer to Algiers to serve as the Director of its investigative team in that area, the occasion has arisen for your detachment from the United States of America Typhus Commission in accordance with previous agreements.  I have therefore given directions for your relief from membership on the Commission and for the issuance of orders to facilitate your move from Cairo to Algiers.
Your service as a member of the United States of America Typhus Commission have been deeply appreciated.  I wish to thank you for your contribution to the accomplishments of the Commission in the first phases of its activities and wish you success in the important new undertaking you will direct for the benefit of civilian public health in North Africa.
Yours very truly,
Henry L Stimson
Secretary of War