In time of war, invasion, rebellion, riot or disaster, or reasonable apprehension thereof, or upon requisition by the President of the United States, the Governor shall order out for active service such portion of the militia as he deems necessary. Whenever it is necessary in case of invasion, disaster, insurrection, riot or breach of the peace, or imminent danger thereof, the Governor may direct the members of the unorganized militia or such of them as may be necessary to be drafted, under such regulations as he may prescribe, into the active service of the state, to serve as directed by him. The Governor may order the organized militia or any part thereof to serve outside the borders of this state in order to perform military duty of every description and to participate in parades, reviews, cruises, conferences, encampments, maneuvers or other training and to participate in small arms and other military competitions and to attend service schools.