Originally posted by proud_savagette
In Article 6 Section 3 of the Constitution it clearly states that "the states shall be bound by oath or affirmation to support this Constitution." They agreed to be part of the Union forever. By seceding, they were breaking the oath they took 72 years beforehand. Then, since they couldn't legally secede, there were also breaking the law stated in Article 1 Section 10 of the Constitution that states "No state shall enter into any treaty, alliance, or Confederation." Obviously, in order to secede from the Union and form their own country, they needed to make treaties and alliances with other states. Article 1 Section 10 also says that, "No state shall, without the consent of Congress, keep troops, or ships of war in times of peace, enter into any agreement or compact with another state, or with a foreign power, or engage in war unless actually invaded, or in such imminent danger." The South was keeping troops, and they attacked and captured Fort Sumter, which was basically an act of war against the United States.
In Article 4 Section 3, it states that "Congress will make rules and regulations for territories and for property of the federal government." The state or territory on its own cannot create the rules for itself. Therefore, when the South seceded, they were taking the property of the federal government since they didn't get permission from Congress to secede or buy the land.
The South believed that Lincoln would abolish slavery if elected president. They had no reason to think this. In his inaugural speech, he said, "I have no purpose, directly or indirectly, to interfere with the institution of slavery in the states where it exists. I believe I have no lawful right to do so, and I have no inclination to do so." This proves that Lincoln wasn't a threat to slavery. The South was being irrational to assume that Lincoln would abolish slavery. He also said, "The states have their status in the Union and they have no other legal status. If they break from this, they can only do so against law and by revolution." Lincoln is clearly stating that secession is illegal.
All in all, the South had no legal, or even moral right to secede. This is proven in the Constitution and also in Lincoln's inaugural speech. Secession is illegal and immoral.