Original sentence: Fearing that slavery would be threatened by results of the federal election, eleven slave states declared their independence from the federal Union and formed a new confederation
Edited sentence: Fearing that slavery would be threatened by results of the federal election, eleven slave states declared their independence from the federal Union of the US Constitution, and reverted to the  Articles of Confederation that preexisted it.However the US Constitution contains language regarding legitimate transfers of territory between states, which is not as yet distinguishing between member states of the Union and those outside the union or new states that may be created in or out of the Union.The secession of the federal territories of Cuba and the Philippines in the years after the Spanish-American War to become independent nations of their own, as well as the several votes on secession by the Commonwealth of Puerto Rico, not to mention the creation of new states out of territory ceded by older states (like the cession of Maine from Massachusetts in the Missouri Compromise of 1820), clearly show the United States has a legitimate process of territorial and state secession