Any officer whose command is called out under the provisions of this chapter and reporting to any civil authority, may require such civil authority to make such instructions in writing and prescribe therein the outline of the duties required of him and his command, and may decline to obey such instructions until put in writing. While such commanding officer must obey all lawful instructions of such civil authorities, such military officer may use his discretion as to the manner of carrying out such lawful instructions as long as he complies with their spirit.