...I think that comparing Grant and Lee is an interesting exercise. I think Grant had a better grasp of the overall strategic dimensions of this war, and when he was put in place as general-in-chief in 1864, he worked out a coordinated strategy for all of the Union armies to operate in such a way as to bring maximum pressure on the Confederacy at all points. Lee, until the very end of the war, never had that kind of authority over all of the Confederate armies, but, rather, was commander of the foremost army, the Army of Northern Virginia. He was probably the best tactical and perhaps theater strategic commander in the war. In some ways, Lee's superiority in that respect may have hurt the overall Confederate military effort because he was so good in his theater that many of the Confederate resources were poured into that theater in Virginia at the expense of other theaters of the war. So there is a kind of ironic dimension to Lee's superiority in that it may have come at the expense of other Confederate armies whose success was necessary if the Confederacy was to succeed.
Read the rest of the interview with historian James McPherson.