The Adjutant General, upon receipt of an application, shall present the long service medal adopted by this state to each soldier or sailor who has completed ten years’ faithful service in the armed forces of the state and for each additional five years’ service therein the adopted clasp in exchange. In the determination of length of service, the term of service of any member of the armed forces of the state with the military or naval forces of the United States in time of war since April 21, 1898, upon proof of honorable discharge from the same, may be added to the number of years served with the armed forces of the state.