General McClellan was an excellent military strategist, but not a very aggressive commander of troops in the field(in battle). Early in the war, after McClellan had been endlessly drilling the Army but not deploying it for battle, Lincoln sarcastically commented "If General McClellan is not going to use the Army, I'd like to borrow it for a while." McClellan was too much of the siege mentality. During the 1862 Peninsular Campaign parts of the Union Army got within about 7 miles of Richmond(their objective)and basically stopped their advance. Lincoln needed a General who was aggressive in battle and that is why he respected Gen. Grant.
NO, Lincoln's problem with McClellan was not military but political. Like most people, McClellan objected to the Radical Republicans' use of the war to push their political agenda and to rape the South. The Radical Republicans in Congress, few of whom had ever done military service, were suspicious of professional military men, particularly those of the upper classes such as McClellan and Fitzhugh Porter. They held hearings on the conduct of the war, and sought to harass and imprison any officer they suspected of "disloyalty" (i.e., not following the radical Abolitionist party line).
The radicals in Congress wanted to fire McClellan long before Lincoln actually did. And Lincoln did not replace McClellan with Grant. He replaced McClellan with Pope and Burnside, who were disasters (but "politically correct"), then Hooker (ditto), and finally Meade, who was a conservative Democrat...but by now Lincoln was running out of Generals. Then Grant came in as Meade's boss. Grant was safe politically because his friend and sponsor was the powerful Illinois Congressman Elihu Washburne, whom Lincoln listened to and obeyed.
US President Lincoln's main concern about General George B. McClellan was in Lincoln's opinion, the failure of McClellan to be more active in taking offensive measures against the Confederacy. McClellan, on more than one occasion, failed to pursue the retreating Army of Northern Virginia. He allowed, as an example, to not pursue Lee's army after the Battle of Antietam. Lincoln was earlier upset that McClellan's attempt to capture Richmond via the peninsula campaign was a miserable failure.
McLellan simply wasn't getting results.
He spent so long making preparations that his plans never got off the ground.
As he was also politically opposed to Lincoln, this caused some of the cabinet to wonder whether he might be a Confederate spy.
Eventually Lincoln said "If General McLellan doesn't want to use the army, perhaps I may borrow it for a while."
Secretary of War, Edwin Stanton, did everything he could to delay the progress of the war. He delayed recruitment and he delayed supplies for the troops. He ordered troop movement in muddy conditions when wagons and horses would get bogged down
The increased death count would generate hate for the south. This hatred for the south would demand punishment and Stanton could declare Martial law. Under Martial law, Stanton could confiscate property and other assets, making himself rich. Lincoln trusted Stanton more than General McClellan. That trust cost the country 100,000's of lives.
General B. McClellan made the following complaint about Stanton.
"adjutant-General's Office U. S. A.
Never in the whole history of nations was anything more absurdly and recklessly managed than the whole system of recruiting, drafting, and organization under the regime of Secretary Stanton. When his actions are coolly criticized, apart from the influence of party feeling, his administration will be regarded as unparalleled in history for blunders and ignorant self-assertion. He unnecessarily prolonged the war at least two years, and at least tripled its cost in blood and treasure.
General B. McClellan"
(George B. McCellan, McCellan's Own Story, Charles Webster & Co. 1897 P229)
Lincoln fired several generals. He fired McClellan twice.
Lincoln's Democratic opponent in the election of 1864 was General George McClellan.
On July 7,1862, Lincoln went to Harrison's Landing to personally know what McClellan's operational plans were. The only thing he got was a letter in which the general, instead of expressing his intention regarding what kind of action he was going to develop on his front, gave a paternalistic suggestions and advice about governmental policy; (source: "Own Story" by George Brinton McClellan, page 487 and following.). It was the second time the general addressed to Lincoln such a kind of message, what would have been enough to sent him before a court martial, but Lincoln didn't react.
Douglas 1860, McCelland 1864
George McClellan ran against Lincoln on a peace platform for the Democrats. He was beaten by Lincoln.
Lincoln was disappointed that General George B. McClellan had allowed Confederate general Lee to escape after the Battle of Antietam. The result of Lincoln's disappointment was the replacement of McClellan by General Burnside.
President Lincoln's preliminary Emancipation Proclamation in 1862 was a shock to General McClellan. He also was shocked when Lincoln soon after suspended habeas corpus. He was opposed to both of these actions by President Lincoln.
When General George B. McClellan returned to Washington DC on March 11, 1862, he became aware that President Lincoln removed his title of general in chief.
General George B. McClellan's departure for his Peninsula campaign gave President Lincoln an opportunity to reorganize the Union's armies. With these plans, Lincoln also made certain changes:* He relieved McClellan as general in chief;* This left McClellan only in charge of the Army of the Potomac;* Under Henry Halleck, Lincoln created the Department of the Mississippi; and* Also, the Mountain Department was created under the command of John Fremont.Lincoln believed he was doing McClellan a favor by allowing him to focus on the major operation at hand, and one that might end the war, namely the capture of Richmond. As general in chief, McClellan would have never approved of the abolitionist General Fremont. Needless to say, McClellan was hugely disappointed with the loss of his most sought after position as general in chief.
As the Union's Peninsula campaign was in its early stages, General McClellan was certain that President Lincoln was hampering McClellan's war operations. Lincoln had stepped in and retained the corps under General McDowell to defend Washington DC. Lincoln believed this was a necessity.
Lincoln's response to General McClellan's command was that Lincoln relieved McClellan of Command.
General George Mcclellan was, by all accounts, an egomaniac. He was bitter over his removal from command by Lincoln. In running for President in 1864 against Lincoln, he sought to "get even" and embarrass Lincoln.
On October 13, 1862, President Lincoln sent General McClellan a long letter explaining the plans Lincoln believed were needed to defeat the South. Lincoln was almost sure that an aggressive Union response from McClellan's army would not be forthcoming. With that said, McClellan had every chance to keep his position if he even tried to execute the plans Lincoln sent to him.
President Lincoln did second guess himself for a while. This is because General McClellan had years of extensive industry and military experience. Lincoln, however, would soon find a replacement for the ousted General.
On April 3, 1862, US President Lincoln is upset that General George B. McClellan has left less than 20,000 troops to guard Washington DC. McClellan was concerned about his Peninsula Campaign. Lincoln refuses to allow any of General McDowell's forces to join McClellan. This causes a rift between Lincoln and McClellan.
he had refused to lee's retreating army into Virginia
That he failed to pursue Lee after Antietam.