When any portion of the military forces of this state shall be in active service of the state, pursuant to this article, the code of military justice and the general regulations for the government of the Armed Forces of the United States shall be considered in force and regarded as a part of this article until such forces shall be duly relieved from such duty. No punishment under such rules and articles which shall extend to the taking of life shall, in any case, be inflicted except in time of actual war, invasion, or insurrection, declared by proclamation of the Governor to exist and then only after the approval of the Governor of the sentence inflicting such punishment.