Miss. Code Ann. § 33-5-9

The unorganized militia, or any part thereof, shall not be subject to any active military duty, except when called into the service of the United States or when called into the service of this state by the Governor in case of war, rebellion, insurrections, invasion, tumult, riot, breach of the peace, public calamity or catastrophe or other state or national emergency or imminent danger thereof. When the militia of this state, or any part thereof, is called forth under the constitution and laws of the United States, the Governor shall first order out for service the National Guard, and then the Mississippi State Guard, or such parts thereof as may be necessary, and if the number available be insufficient, he shall then order out such part of the unorganized militia as he may deem that the necessity requires.