18. A sailor shall be entitled to be released at the expiration of the term of service for which he is engaged unless-(a) such expiration occurs,ÔÇö(i) when war is imminent or existing, or(ii) when the strength of the branch of service to which he belongs is five per cent below its strength, in which case he shall be liable to continue to serve for such further period as may be required by the Chief of Naval Staff; or(b) he is re-engaged in accordance with the regulations.