The militia of the state of Idaho shall consist of all able-bodied citizens of the state, and all other able-bodied persons who have or shall have declared their intentions to become citizens of the United States and are residents of the state of Idaho; who shall be more than eighteen (18) years of age, and except as hereinafter provided, not more than forty-five (45) years of age, subject to the following exemptions:
(1) Persons exempted from service in the militia by the constitution of the state of Idaho and by the laws of the United States from enlistment or draft into the regular army. Provided, however, that voluntary enlistments, with the written consent of the parent or guardian of any able-bodied citizen over the age of sixteen (16) years may be accepted and such enlistees inducted into the organized militia of the state of Idaho in time of war, and as classified in section 46-103, Idaho Code, except that the provision for the enlistment of able-bodied citizens under the age of eighteen (18) years will terminate six (6) months following the declaration of peace.