Yes I think they had the right to seceed, but they didn't follow the legal Constitutional proceedures to seceed. Once admitted to the union by a vote of the Congress and ratified by the states, they must permit a vote by the Congress and ratification by the states to allow them to leave. A state cannot be allowed to seceed from the nation simply for its own interests, it must also be in the national interests. It's what makes us a federal republic, rather than a group of loosely allied states, like Germany and Italy were at the time, or the Soviet Union in our time.
One of the more notable of the Founding Fathers would seem to disagree: From the pen of Thomas Jefferson: "[T]he several states composing the United States of America are not united on the principle of unlimited submission to their general government; but that, by compact, under the style and title of the Constitution of the United States, and of certain amendments thereto, they constituted a general government for general purposes, delegated to that government certain powers, reserving, each state to itself, the residuary mass of right to their own self-government; and that whensoever the general government assumes undelegated powers, its acts are unauthoritative, void and of no effect."
This personal opinion is not a law and it only affirms the federal system. It doesn't not refer to secession at all. It reserves, for the states, the bulk of governmental functions and suggests that a national government that "assumes undelegated powers" can be ignored by a state. It does not mention any right to seceed. Jefferson was a southern slave-owner, you know, and he was against any federal attempt to legislate slavery, which he held to be a state issue. And so it was until we fought a civil war to settle the slavery issue.
Personal opinion of one who had a major role in the development of the document. He would be well aware of the intent of the document, more so than federal judges justifying the victors stance after the war's occurrence. The fact that the Constitution was ratified with participants reserving the right to terminate the union shows acknowledgment of rights of secession. From the time of the Hamiltonians, a power and money grab began taking place to the benefit of the industrialized North. To place the cause of the civil war on the issue of slavery is to discount 70+ years of discord on issues of centralization and hegemony.
Show me liegislation northern congressman introduced to limit or eventually abolish slavery. Even during the war northen states were importing slaves to sell. The Confederate constitution ourlawed the importation of slaves. It is also worth mentioning that the Confederate Congress was considering abolition near the end of the war. It may have only been to create a new source of troops, but if the south were truly fighting to keep slavery alive then they would have never even considered such a practice.
As far as the secession, it was certainly constitutional and the southern states did not need permission of the federal government to secede. The powers of the federal government or delegated powers. That implies that the states are the stronger of the bodies. The states existed idependently before the union, the joined the union, and had the right to leave under any circumstances they seemed necessary.
1777 - Slaves emancipated in Massachusetts; slavery abolished in Pennsylvania; the constitution of the state of Vermont prohibits slavery. 1783 - New Hampshire abolishes slavery 1784 – Rhode Island and Connecticut pass emancipation laws. 1786 - Slavery abolished in Vermont. 1800 - U.S. enacts stiff penalties for American citizens serving voluntarily on slavers trading between two foreign countries 1802 - Ohio slavery prohibited by the state constitution 1804 – New Jersey adopts a policy of emancipation 1808 - U.S. abolition of the slave trade takes effect prohibiting the importation of African slaves into the U.S. 1816 - Indiana slavery prohibited by the state constitution 1818 - Illinois slavery prohibited by the state constitution 1819 - The U.S. Congress passes legislation stiffening provisions against American participation in the slave trade 1821 - The Missouri Compromise, measures passed by the U.S. Congress to end the first of a series of crises concerning the extension of slavery. 1827 - Slavery abolished in New York. 1842 - Britain & U.S. signed Webster-Ashburton Treaty, banning slave trade on high seas 1846 - Wilmot Proviso, amendment to a bill put before the U.S. House of Representatives during the Mexican War stipulating that none of the territory acquired in the Mexican War should be open to slavery 1849 - The Fugitive Slave Law passed in the United States 1850 - The Compromise of 1850, concerning the question of the extension of slavery into the territories annexed from Mexico after the Mexican War. 1854 - The Kansas-Nebraska Act, flatly contradicted the provisions of the Missouri Compromise These are just the major legislation. Literally dozens of proposals defending or opposing slavery were introduced in the 30 years leading up to the Civil War. I especially draw your attention to the Wilmot Proviso. Not true, see above. The United States outlawed the imporation of slaves in 1808 and stiffened the penalties in 1819. OK, now you show me where this is spelled out in the Constitution. I think you are reading your personal opinion into it.
Or it may be the other way around. The Articles of Confederation mention a perpetual Union, yet that did not stop anyone from nullifying that relationship to begin a new one. The Constitution does not claim a perpetual Union, and some states reserved the right to take back those powers. When Jefferson writes "reserving, each state to itself, the residuary mass of right to their own self-government" it is pretty clear what he thought the document he helped write meant. Just because it doesn't agree with those who waged war against an independent South doesn't make it any less valid. That those who waged war against the South and stole the land of Virginia to create a new State in direct contradiction to the Constitution does not seem to trouble you. Of course, if the States did have the right to secede and it was really just a war of occupation, then the Constitution doesn't apply in this matter.