What orders did halleck change concerning the AoP? Or for any army after Grant was named GiC?
I found an interesting in depth study on Grant, I will share it with you here,
Grant and Insubordination
Grant had a fertile military mind and often saw what needed to be done to serve the broader purpose of an individual campaign or the war. His prescience about needful actions often led him to take the initiative rather than waiting for orders from his superiors. He would send messages saying that he was going to do such-and-such with the forces under his command unless he received orders to the contrary. This insubordination led some superiors to be critical of Grant.
Immediately before the Battle of the Big Black River, General Halleck sent an order to Grant to move his Army of the Tennessee back to Grand Gulf. Grant’s troops had already crossed the Mississippi and commenced the lightning campaign that would end in the surrender of Vicksburg. Grant told the delivering officer that he would not obey the order. The order was out of date, Grant argued, and if Halleck knew Grant’s position now, the commanding general would not have given the order. The messenger disagreed, arguing that Grant should obey the order at once. Grant relates that there was just then a loud cry and a charge. “I immediately mounted my horse and rode in the direction of the charge, and saw no more of the officer who delivered the dispatch.”
[89] In this way Grant conveniently escaped from the officer bearing Halleck’s inconvenient order.
As Grant rose in rank he interacted increasingly more with the military and political authorities in Washington, who often peppered him with dispatches. In October and November of 1863, the authorities in Washington were gravely worried about the tenuous position of General Burnside in Knoxville. The dispatches said that Lincoln was “much concerned.”
[90] Grant answered the dispatches as well as he could, but argued that logistical considerations precluded the relief by reinforcement that Washington so desired. “We had not at Chattanooga animals to pull a single piece of artillery,” Grant pointed out, “much less a supply train.” While sending reinforcements to Burnside seemed like an unalloyed good to those in Washington, Grant pointed out that considerations of supply told a different story. “Reinforcements could not help Burnside,” Grant argued, “because he had neither supplies nor ammunition sufficient for them; hardly, indeed, bread and meat for the men he had.”
[91] Eventually, Grant relieved Burnside in his own way and in his own time, and did not permit the pressure from Washington to divert his efforts.
Grant’s superiors were not satisfied with just peppering him with dispatches, however. At times they overruled his orders to his subordinates. Secretary of War Stanton insisted that he personally approve all of Grant’s orders. Grant’s directives would languish on Stanton’s desk, sometimes for days, until the Secretary approved them. Grant did his best to stop this practice but notes that any success he had was temporary, and that Stanton would lapse into his old habits not long after. “I remonstrated against this in writing, and the Secretary apologetically restored me to my rightful position of General-in-Chief of the Army. But he soon lapsed again and took control much as before.”
[92]
As head of the Union Army Grant experienced intense pressure “to desist from his own plans and pursue others.”
93 Sometimes Grant would have to bypass the political authorities in Washington to evade their interference with his orders to his subordinates. Grant had an important and somewhat unlikely ally in these circumventions: the President of the United States. Grant relates in his memoir how their “conspiracy” against the caution of political leaders in Washington contributed to the ultimate success of the campaign in the Shenandoah Valley in 1864.
Grant knew that the Shenandoah Valley “was very important to the Confederates, because it was the principal storehouse they now had for feeding their armies about Richmond.”
[93] Grant, therefore, ever striving to worry his adversary, wanted to chase the enemy from the valley. On August 1, 1864, he sent an order with General Sheridan—along with reinforcements to protect Washington—that he should “put himself south of the enemy and follow him to the death. Wherever the enemy goes let our troops go also.”
[94] President Lincoln saw this dispatch from Grant and approved wholeheartedly. However, Lincoln told Grant to look over the dispatches emanating from Washington, because Grant would find no evidence there that anyone in Washington was contemplating such a pursuit “to the death.” Lincoln informed Grant that no such pursuit would happen unless Grant himself “watch[ed] it every day, and hour, and force[d] it.”
[95] If it were to happen, Lincoln assured Grant, the General-in-Chief himself would have to use his authority to head off every attempt to dilute his aggressive plan of pursuit.
Following Lincoln’s advice, Grant visited Sheridan in the field and did not send his orders through Washington. Had he sent his orders through Washington, Grant observes, “they would be stopped there and such orders as Halleck’s caution (and that of the Secretary of War) would suggest would be given instead, and would, no doubt, be contradictory to mine.”
[96] This would appear to be blatant insubordination, until one considers that Grant had Lincoln’s blessing. Grant understood that the leaders in Washington were cautious because they wanted to avoid a major military defeat before the elections of 1864, and so hand the election to the Democrats. After all, those gathered for the Democratic convention that year had “declared the war a failure.”
[97] Lincoln was not so cautious (or fearful) as the members of his cabinet. Thanks to Lincoln and Grant, despite the trepidation of some political leaders in Washington, Sheridan’s operations resulted in a major victory. As Grant put it, “this decisive victory was the most effective campaign argument in the canvas.”
[98]
Despite his occasional insubordinations, Grant understood where his military authority stopped and political authority became supreme. Here too Lincoln was a key figure for Grant. The relationship of Lincoln and Grant was based on mutual respect, even admiration. Grant used his skill for character assessment on Lincoln and found the President extremely admirable. “He always showed a generous and kindly spirit toward the Southern people, and I never heard him abuse an enemy. Some of the cruel things said about President Lincoln, particularly in the North, used to pierce him to the heart; but never in my presence did he evince a revengeful disposition.”
[99]“He was a great man,” Grant said of Lincoln, “a very great man. The more I saw of him, the more this impressed me. He was incontestably the greatest man I ever knew.”
[100]
Lincoln made it clear to Grant where the boundary of acceptable insubordination lay. As Lincoln confided in Grant, the President did not want to interfere in military matters but the “procrastination on the part of commanders, and pressure from the people at the North and Congress” compelled him to do so on a number of occasions.
[101] It was good that Lincoln did not take a firmer hand with his military subordinates because he was not necessarily gifted in the art of war. (At one point Grant relates how Lincoln shared a plan of campaign with him that had serious flaws. Ever tactful, Grant did not point this out to the President at the time.
[102] ) While respecting Grant’s authority, Lincoln was careful to show Grant where the boundary was between military and political authority. When Lincoln came to Fort Monroe to meet with the peace commissioners from the South, he would not allow any military officers to participate in the discussions.
[103]And when the prospect of a meeting between Lee and Grant materialized near the end of the war, Lincoln warned Grant through Stanton that Grant was “not to decide, discuss, or confer upon any political questions.”
[104] Grant received and internalized Lincoln’s admonition.
While Grant was closing in on the Army of Northern Virginia, a correspondence began between himself and Lee. During the exchange, whenever Lee strayed into questions of peace terms to end the war rather than the surrender of his army, Grant replied that such political questions were beyond his remit. “I have no authority,” Grant reminded Lee, “to treat on the subject of peace.”
[105] While Grant bridled at political interference in military operations, he was clearly aware of and respected the bounds of his authority and his ultimate subordination to political authority. Lincoln helped remind Grant of this fact, even while helping his general circumvent political interference in military operations.
While Grant fought against this political interference in his operations, he appreciated that the opposing general was subject to similar pressures. After the bloody battle of Cold Harbor, Grant decided to make another left flank maneuver in his Virginia campaign. Grant realized that this maneuver was dangerous but necessary. If Lee perceived that Grant was moving and did not follow him, the Confederate general might attack Butler’s army and destroy it before Grant’s army could come to its relief, defeating much of the Union force in detail. However, Grant “relied upon Lee’s not seeing [Grant’s] danger as [Grant] saw it.”
[106] This was because Grant had presented the Confederates with an even greater danger: the security of their capital, Richmond. Grant relied on his adversaries’ preoccupation with their own danger. Even if Lee discounted this danger, Grant reasoned, “I knew that [Richmond’s] safety would be a matter of the first consideration with the executive, legislative and judicial branches of the so-called Confederate government, if it was not with the military commanders.”
[107]
In essence, I would argue, Grant was relying on the political leaders in the South to hinder bold actions by Lee to the same extent that Grant’s political superiors had tried to hinder his operations. This threat to their seat of power threatened their control over the Confederate States, which threatened their protraction of the conflict. By threatening the Confederate capital Grant induced worry, a perception of danger, in his adversaries at the political level such that they would likely interfere with any military operations that might increase the danger. Grant, it would appear, used his knowledge of the conflicts that can arise between the military and the political sphere in strategy to his advantage.
The strategist occupies the nexus between the military arts and the political arts. If war is the continuation of politics with the admixture of other means, as Clausewitz contends, then political authorities should predominate. As Grant’s calculated insubordination shows, however, military leaders occasionally need to press political authorities to follow through with their own stated policy. At the same time, it is important for political leaders to instruct their military subordinates on the limits of their authority, as Lincoln did with Grant. Finally, an astute strategist who understands what kinds of actions induce political interference in military operations can exploit this tendency of politicians to undermine an adversary’s effective use of military forces.
https://classicsofstrategy.com/2021/02/14/ulysses-s-grants-civil-war-memoir-and-strategy/