Great discussion. Hopefully not too late to cast a vote.
Grant was a great commander, no question. One of the greatest in American military history. He knew what had to be done, knew he had the resources to do it, and relentlessly, with great nerve and skill, pressed his advantages in men and materiel to final victory.
The Wilderness in May 1864 doesn't get as much attention as epic battles like Antietam and Gettysburg, but it's a critical illustration of the point. It was Grant's first encounter with Lee and in many ways, at the tactical level, could be counted a Confederate victory.
Grant's army was stopped and took heavy losses, significantly more than suffered by Lee's forces. It was at that point in previous years that Union generals would have withdrawn to regroup, lick their wounds, and wait to fight another day. Not Grant. He disengaged and moved...south, setting the stage for a horrifically bloody month that would see his army take 50,000 casualties but inflict damage on southern forces that ultimately broke their back.
All this said, and taking nothing away from Grant, I have to vote for Lee as the greatest general of all. I put him in my top-5 all-time ever anywhere list. It didn't hurt that for much of the war he had the benefit of arguably the most talented collection of general officers ever assembled in one American army -- not to mention the command of one of the toughest and most ornery forces in history.
Yeah, yeah...the third day at Gettysburg. An epic blunder, no doubt. But there's no commander in the history of warfare who never made a mistake. Besides, if Jackson had been around on the first day of the battle, as opposed to Ewell who replaced him after Chancellorsville, there might never have been a third day at Gettysburg. The Union army might have been driven off the field before then.
At the end of the day, this is like arguing about the greatest President or the greatest football team or the greatest whatever. There's lots of good ammunition for different points of view...but it's not ultimately something that can be scientifically proven or conclusively judged.
Still, it's fun.
Thank you, gentlemen, and carry on.