LISTEN CAREFULLY:
10 US Code Chapter 13 (Insurrection Act)
Legla basis for commencement of the Civil War
§ 253.[1] Interference with State and Federal law
The President, by using the militia or the armed forces, or both, or by any other means, shall take such measures as he considers necessary to suppress, in a State, any insurrection, domestic violence, unlawful combination, or conspiracy, if it—
(1) so hinders the execution of the laws of that State, and of the United States within the State, that any part or class of its people is deprived of a right, privilege, immunity, or protection named in the Constitution and secured by law, and the constituted authorities of that State are unable, fail, or refuse to protect that right, privilege, or immunity, or to give that protection; or
(2) opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws.
In any situation covered by clause (1), the State shall be considered to have denied the equal protection of the laws secured by the Constitution.
Now Anons CONTRAST wikipedia BULLSHIT says Act LIMITS the President! (Mikrobot here)
The Insurrection Act of 1807 is a United States federal law (10 U.S.C. §§ 251–255) that governs the ability of the President of the United States to deploy military troops within the United States to put down lawlessness, insurrection, and rebellion. The general purpose is to limit presidential power, relying on state and local governments for initial response in the event of insurrection. Coupled with the Posse Comitatus Act, presidential powers for domestic law enforcement are limited and delayed.