How is Robert E. Lee a "great American" when he engaged in treasonous rebellion against the U.S. government.
He resigned his commission in the U.S. army and fought to defend his home (Virginia) and family from the yankee invaders. To have done otherwise would have been the real treason.
Answer this, then I will answer you.
How are Geroge Washington, Patrick Henry, Thomas Jefferson, etc..., great Americans when they "engaged in treasonous rebellion" against the British Crown?
"How is Robert E. Lee a "great American" when he engaged in treasonous rebellion against the U.S. government."
History has already judged him as such. It's just the way it is.