Section 49. Upon the termination of any service of the armed forces of the commonwealth under a precept in accordance with section forty-two, or under an order of the commander-in-chief at the request of such sheriff, mayor, city manager or selectmen under section forty-one, the adjutant general shall certify to the state treasurer the expense of said service, and the state treasurer shall thereupon assess said expense in the manner provided for by section twenty of chapter fifty-nine.