Section 89. Under an order issued by the commander-in-chief, the adjutant general, in the name and on behalf of the commonwealth, may, for military use, accept the gift or loan of a motor vehicle, or the grant of the temporary right to the use and control of a motor vehicle, or hire or purchase a motor vehicle in the event—
(1) An enemy at war with the United States shall commence or threaten operations to endanger the peace or safety of the commonwealth; or
(2) Of tumult, riot, mob, natural disaster, or public catastrophe within the purview of section forty-one or forty-two; or
(3) Any unit of the armed forces of the commonwealth shall be directed or authorized by order of the commander-in-chief to participate or engage in any military training, exercise or duty in which the use of motor vehicles in excess of the number issued to such unit may be required.