Each officer and employee of any town, city or borough who is a member of the reserve corps of any branch of the armed forces of the United States, as defined in § 27-103, shall be entitled to absent himself from his duties or services while engaged in required field training in such reserve corps. No such officer or employee shall be subjected by any person, directly or indirectly, by reason of such absence, to any loss or reduction of vacation or holiday privileges or be prejudiced by reason of such absence with reference to promotion or continuance in office or employment or to reappointment to office or to reemployment. While engaged in such training, each officer or employee who is a bona fide member of the reserve corps of any branch of the armed forces shall receive the difference between his compensation for military activities and his salary or compensation as such officer or employee, provided, if his compensation for military activities exceeds the amount due him as such officer or employee, his military compensation shall prevail. The period of absence in any calendar year shall not exceed thirty days.