The country that he served at West Point? The United States. The country that he fought for against Mexico? The United States.
You are assuming that the Union = the United States, which, in 1861, was not the case.
He had a decision to make, whom shall you serve - the Union, or the Confederacy. He chose to serve Virginia, and by extension, the Confederacy.
If he were a traitor, why didn’t he serve the Union and serve poorly? Is Lee, who fought well and bravely for the Confederates more of a traitor than McLellan, who ran on a platform of reconciliation with the South, against Lincoln, and who’s policy of war directly lead to it’s extension?
Assuming as Lee's cousin Samuel Philips Lee who fought with the US Navy did. Or as Lee's brother, John Fitzgerald Lee who served in the US Army Judge Advocate General Corps did. Or as Lee's sister Anne Lee Marshall and her son who served in the Union Army did.
It really was a war of brother against brother. There was no established belief that loyalty to a state overrode loyalty to the country -- especially not among career soldiers and sailors. I suspect in Lee's case, it wasn't so much state or family tradition that carried the day. If he fought for the United States, he'd probably be fighting against his own children, and he couldn't do that.
It was a tragic choice he made. But it wasn't the right one.
Is Lee, who fought well and bravely for the Confederates more of a traitor than McLellan, who ran on a platform of reconciliation with the South, against Lincoln, and who’s policy of war directly lead to it’s extension?
That would be an easy yes.
Politicians will always argue about whether to fight wars and how to fight them, but to take up arms against one's own country is something else altogether.
“You are assuming that the Union = the United States, which, in 1861, was not the case.”
You are correct. The CSA never legally existed.
The Supreme Court ruled in Texas v. White (1869) that unilateral succession is illegal and that the southern states never legally succeeded.
“The Union of the States never was a purely artificial and arbitrary relation. It began among the Colonies, and grew out of common origin, mutual sympathies, kindred principles, similar interests, and geographical relations. It was confirmed and strengthened by the necessities of war, and received definite form and character and sanction from the Articles of Confederation. By these, the Union was solemnly declared to ‘be perpetual.’ And when these Articles were found to be inadequate to the exigencies of the country, the Constitution was ordained ‘to form a more perfect Union.’ It is difficult to convey the idea of indissoluble unity more clearly than by these words. What can be indissoluble if a perpetual Union, made more perfect, is not?”
“When, therefore, Texas became one of the United States, she entered into an indissoluble relation. All the obligations of perpetual union, and all the guaranties of republican government in the Union, attached at once to the State. The act which consummated her admission into the Union was something more than a compact; it was the incorporation of a new member into the political body. And it was final. The union between Texas and the other States was as complete, as perpetual, and as indissoluble as the union between the original States. There was no place for reconsideration or revocation, except through revolution or through consent of the States.”
“Considered therefore as transactions under the Constitution, the ordinance of secession, adopted by the convention and ratified by a majority of the citizens of Texas, and all the acts of her legislature intended to give effect to that ordinance, were absolutely null. They were utterly without operation in law. The obligations of the State, as a member of the Union, and of every citizen of the State, as a citizen of the United States, remained perfect and unimpaired. It certainly follows that the State did not cease to be a State, nor her citizens to be citizens of the Union. If this were otherwise, the State must have become foreign, and her citizens foreigners. The war must have ceased to be a war for the suppression of rebellion, and must have become a war for conquest and subjugation.”
“Our conclusion therefore is that Texas continued to be a State, and a State of the Union, notwithstanding the transactions to which we have referred. And this conclusion, in our judgment, is not in conflict with any act or declaration of any department of the National government, but entirely in accordance with the whole series of such acts and declarations since the first outbreak of the rebellion.”