Halleck's "kicking Grant upstairs" was his attempt to remove Grant. One must give Halleck his due. He was a masterful "insider" politician who had great instincts for sensing who was the greatest threat to his ambitions. When Lincoln called Halleck to Washington to become General in Chief, Halleck no longer had to worry about Grant as a revival; instead, he could build Grant back better so that he and Buell's successes would become further evidence of how much Lincoln needed Halleck to be in overall charge. (Halleck was careful to make certain that Grant had no more soldiers than Buell.) The great irony is that Halleck could have achieved his ultimate ambition - to be President - if he had simple let Grant be the field commander. When Halleck went back East, he discovered that his ego was going to be matched by those of Pope, McClellan and Burnside and Stanton. They were not going to take orders and work towards victory as Grant had. What saved him was Grant's lack of malice and appreciation for what Halleck did well; instead of thinking about paying Halleck back for his political back stabbing, Grant made him Chief of Staff and then arranged for Halleck to be able to return to his home state of California in triumph.The battle provided PLENTY of opportunities to adversely impact the careers of both and it was largely luck that prevented their disgrace and removal. Grant could easily have made his friend Sherman the scapegoat for most of the gaffes made by Federal forces prior to the battle - I can certainly imagine any of the other Federal commanders at the time - McClellan, Halleck, Pope, Burnside, etc., etc. - eagerly grasping the opportunity to save their own skins by throwing Uncle Billy under the bus! In fact it's a wonder that Halleck didn't take the same opportunity to remove Grant instead of just kicking him upstairs into the do-nothing and dead-end position of Second-In-Command during the subsequent advance on Corinth.