In order to be commissioned or enlisted in such force, a person must meet the following qualifications:

1. (a) be a citizen of the United States or a person who has declared an intention to become a citizen of the United States;
2. (b) have not been dishonorably discharged from any military or naval organization of this State, another state, or the United States;

3. (c) be at least seventeen years old.

   In carrying out the provisions of this chapter, preference shall be accorded veterans of former wars so far as may be consistent with the public interest and both males and females may serve in such force as officers and as enlisted persons.