As Admiral Nimitz is purported to have lectured his staff in preparing for the Battle of Midway, "McClellan was a great little organizer, but he couldn't act." Grant, on the other hand, didn't always know for sure where he was going, but he opted for "going"
rather than standing still...Lincoln wanted a commander of action; he saw Lee wasn't going to sit around and cede the initiative to the Union; Lincoln needed a general who was going to act decisively, and Grant, for his other failings, was decisive....
It may have been also that Robert E. Lee had much to do towards making McClellan a good field commander. That McClennan in a sense was a failure, ( strictly opinion) however the Commander In Chief has to make correct decisions.. Lincoln clearly failed as much as the generals that he chose. As for Grant, a fine general, but his appointment as leader of the Army of the Potomac and his successes had much to do with his superior strength of arms in terms of numbers, his manufacturing advantage thanks to a developed economic system in the North.
One has to wonder how Lee would stack up against Grant if they had access to more equal men & equal supplies.
He was very successfully at raising and training the army. He was ineffective as a tactical commander in the field.
On July 26th 1861, George McClellan was appointed commander of the army of the Potomac. He was a Human.
George Brinton McClellan
The commander of the Unions Army of the Potomac at Antietam was Major General George B. McClellan.
George McClellan
George McClellan
George McClellan
George McClellan
George McClellan
George McClellan
McClellan was a Union commander and he repelled general Lee's first Northern invasion.
Robert E. Lee, AND George McClellan