“I have made certain terms with Lee – the best and only terms. If I had told him and his army that their liberty would be invaded, that they would be open to arrest, trial and execution for treason, Lee would never have surrendered. I will resign the command of the army rather than execute any order directing me to arrest Lee or any of his commanders, so long as they obey the laws.” ~ General Grant upon learning of Lee’s indictment for treason
Though Lee was originally opposed to secession, he made his opinion clear in his response to being offered the command of Federal forces at the onset of hostilities:
"...though opposed to secession and a deprecating war, I could take no part in the invasion of the Southern States." ~ From Lee's reply to Francis Blair
Not one Confederate was ever tried for treason, though several were indicted. Lee was a true patriot, choosing family & country over "government." Lee resigned his commission rather than disobey an order. Since he believed, given his choices, that this was the only moral option he had, I think Lee made an honorable choice. Lee lost his citizenship. Can a non-citizen commit treason? Did Lee, in resigning his commission and joining the CSA, effectively renounce his citizenship or did the Federal government take it from him as a result of his actions? I suppose it depends, at least in part, on one's perspective. If Lee was a traitor (and I don't believe he was), he would be the only traitor for which a ship in the United States Navy was ever named. He would be the only traitor in Statuary Hall at the U.S. Capitol. He would be the only traitor whose image was used in a positive way to recruit military personnel to fight and win WWII. Quite an accomplishment for a "traitor", wouldn't you say?
According to the source for the recruiting poster image, ". . . recruiting efforts in Virginia were bolstered by invoking Lee's memory." Hmmm, rather contradictory, if you are to believe how some paint Lee's actions and how he should be remembered. The Federal government using Lee's image to recruit volunteers to fight in the U.S. Army? Why did it work? How is it that Lee's image attracted recruits to the same organization he ostensibly betrayed as a "traitor?" So the U.S. military used a positive and affirming depiction of a "traitor" to attract recruits to the same military that this "traitor" supposedly betrayed and to defend the same Nation he supposedly committed treason against? Yeah, works for me.
Depicting Lee as a "traitor" and "treasonous" is simply shallow, simplistic historiography. Presentism in historical interpretation just doesn't work.
(Images are from the Virginia Historical Society's website.)