On March 30, 1861, on accepting his promotion to colonel, R. E. Lee took an oath that said, in part, "I will bear true allegiance to the United States of America, and that I will serve them honestly and faithfully against all their enemies or opposers whatsoever."
Less than a month later, on April 20, with the United States facing an enemy, instead of serving the United States honestly and faithfully against that enemy, he sent in his resignation.
Did he have his fingers crossed on March 30? Did he mutter under his breath, "Except for southern states" when he was taking the oath?
Brian Steel Wills describes Thomas' view:
"George Thomas took such an oath as a sacred trust. He was especially critical of those brethren in the old blue who claimed some justification for violating theirs. In his eyes there could be none. In this regard, as he told another officer, these former comrades 'had sworn allegiance to the government [and] they were bound to adhere to it, and would have done so [if] they had been so inclined. He dismissed constitutional explanations particularly as poor 'excuses,' noting that the 'government to which they had sworn allegiance remained, and as long as it did exist, I should have adhered to it.' " [Brian Steel Wills, George Henry Thomas: True as Steel, pp. 101-102]
Ulysses S. Grant took this view: "We are now in the midst of trying times when every one must be for or against his country, and show his colors too, by his every act. Having been educated for such an emergency, at the expense of the Government, I feel that it has upon me superior claims, such claims as no ordinary motives of self-interest can surmount. I do not wish to act hastily or unadvisedly in the matter, and as there are more than enough to respond to the first call of the President, I have not yet offered myself. I have promised, and am giving all the assistance I can in organizing the company whose services have been accepted from this place. I have promised further to go with them to the State capital, and if I can be of service to the Governor in organizing his state troops to do so. What I ask now is your approval of the course I am taking, or advice in the matter. A letter written this week will reach me in Springfield. I have not time to write to you but a hasty line, for, though Sunday as it is, we are all busy here. In a few minutes I shall be engaged in directing tailors in the style and trim of uniform for our men.
"Whatever may have been my political opinions before, I have but one sentiment now. That is, we have a Government, and laws and a flag, and they must all be sustained. There are but two parties now, traitors and patriots and I want hereafter to be ranked with the latter, and I trust, the stronger party. I do not know but you may be placed in an awkward position, and a dangerous one pecuniarily, but costs cannot now be counted. My advice would be to leave where you are if you are not safe with the views you entertain. I would never stultify my opinion for the sake of a little security."