Any person who shall knowingly or willfully obstruct, resist or oppose any policeman or other officer of the City authorized to make arrests, in serving or attempting to serve any lawful process or order of the City magistrate or of any court of the City, or in the performance of any official duty, or who shall assault or beat any such officer or person duly authorized, when serving or executing, or attempting to serve or execute, or because of having served or executed, or attempted to serve or execute, any order or process of official duty, or when engaged in the performance of any official duty, shall be guilty of a misdemeanor. (Code 1962, § 27-51)