Robert E. Lee was the greatest American general in history and deserves much more respect than he's given these days. Instead of whitewashing history into what makes people feel good, history should be preserved in a fair, even-handed way.
Did you go to Benedict Arnold High School by any chance or do you just like traitorous scum?
Regardless of what you think about the Civil War, Lee was a great general, and as mentioned by Kingpoleon, was simply loyal to Virginia before the Union, which was a common attitude at the time. In my opinion, and those of many non-Southern historians, Lee was a greater general than Winfield Scott, Ulysses Grant, or any other general that fought under the US flag.
And yes, since I was born British, I've always considered Benedict Arnold to be a hero.