First, let's dispense with that familiar dishonest device of politics of confusing "country" with "nation" (as in "Ask not what your country...?). A nation is a creation and tool of the politicians, associated, but not identical with, a geographical region and its population, the country. Do we owe a duty to the nation? I don't think so, the nation exists to meet needs of the governing class and their clients, not our fellow countrymen. For this reason, as I see it, Southerners owed no duty or allegiance to the Union or to the Federal Government. In a Republic, the government is supposed to be the servant of the people. The government owes a duty to the people; the people do not owe a duty to the government. This is one point on which the founding fathers, some of them at least, had some serious confusion. They did not adequately eliminate all features of royal government in their attempt to create a republican government.
""The name of American, which belongs to you in your national capacity, must always exalt the just pride of patriotism, more than any appellation derived from local discriminations. With slight shades of difference, you have the same religion, manners, habits, and political principles -- you have in a common cause fought and triumphed together; the independence and liberty you possess, are the work of joint counsels, and joint efforts, of common dangers, sufferings, and successes...These considerations speak a persuasive language to every reflecting and virtuous mind, and exhibit the continuance of the Union as a primary object of patriotic desire. Is there a doubt whether a common government can embrace so large a sphere? Let experience solve it. To listen to mere speculation in such a case were criminal. We are authorised to hope that a proper organization of the whole, with the auxiliary agency of governments for the respective subdivisions, will afford a happy issue to the experiment. With such powerful and obvious motives to union, affecting all parts of our country, while experience shall not have demonstrated its impracticability, there will always be reason to distrust the patriotism of those who in any quarter may endeavour to weaken its hands." -- George Washington.
Had Washington been alive in 1861 he would have been first in line to offer his services to Abraham Lincoln.