Executive Order—General Orders: 18
HEADQUARTERS OF THE ARMY,
The President directs that the following change be made, at the request of Major-General Thomas, in the assignment announced in General Orders, No. 10, of March 11, 1867, of commanders of districts, under the act of Congress entitled "An act to provide for the more efficient government of the rebel States," and of the Department of the Cumberland, created in General Orders, No. 14, of March 12, 1867:
Brevet Major-General John Pope to command the Third District, consisting of the States of Georgia, Florida, and Alabama; and Major-General George H. Thomas to command the Department of the Cumberland
By command of General Grant:
Assistant Adjutant-General .
Andrew Johnson, Executive Order—General Orders: 18 Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/201917