Any employee or official shall be granted a leave of absence for the purpose of receiving an armed forces pre-induction physical examination upon order issued by the selective service system or otherwise entering upon active federal military service. If not accepted for such service, the employee or official shall promptly be reinstated in his position without loss of seniority or status, or reduction in his rate of pay and without prejudice. During such period the employee or official shall for all purposes be considered to have rendered services find to have been compensated therefor at his regular rate of pay.