Hooker led his corps (now designated the XX Corps) competently in the 1864 Atlanta Campaign under Sherman, but asked to be relieved before the capture of the city because of his dissatisfaction with the promotion of Maj. Gen. Oliver O. Howard to command of the Army of the Tennessee, upon the death of Maj. Gen. James B. McPherson. Not only did Hooker have seniority over Howard, but he also blamed Howard in large part for his defeat at Chancellorsville (Howard had commanded the XI Corps, which had borne the brunt of Jackson's flank attack). Hooker's biographer reports that there were numerous stories indicating that Abraham Lincoln attempted to intercede with Sherman, urging that Hooker be appointed to command the Army of the Tennessee, but Sherman threatened to resign if the president insisted. However, due to "obvious gaps" in the Official Records, the story cannot be verified.