July 1862 Lincoln appointed Halleck General-in-Chief of all Union forces hoping his administrative skill would help in Washington https://play.google.com/store/books/details/Georgiann_Baldino_An_Imperfect_Union?id=sn-LCgAAQBAJ
Henry Wager Halleck (1815-1872) was a United States Army officer, scholar, and lawyer. A noted expert in military studies, he was known by a nickname that became derogatory, "Old Brains." He was an important participant in the admission of California as a state and became a successful lawyer and land developer. Early in the American Civil War, he was a senior Union Army commander in the Western Theater and then served for almost two years as general-in-chief of all U.S. armies.
"September 21, 1863. To: Major-General HALLECK: I think it very important for General Rosecrans to hold his position at or about Chattanooga." Abraham Lincoln Lincoln's decision to hold Chattanooga went on to have a profound effect on the course of the Civil War. The LOC image probably taken when Chattanooga was the base for Sherman's Atlanta campaign. http://asoldiersfriend.com/