The commanding officer of any portion of the militia parading or performing any military duty in any street or highway may require persons in such street or highway to yield the right of way to such militia, except that the carriage of the United States mail, the legitimate functions of the police, and the progress and operations of hospital ambulances, fire engines, and fire departments and apparatus shall not be interfered with thereby. Any person who hinders, delays, or obstructs any portion of the militia parading or performing any military duty, or who attempts so to do, is guilty of a misdemeanor.