what is a historical documentary
First -- let's look at this definition of documentary from Dictionary.com.
2. Movies, Television. based on or re-creating an actual event, era, life story, etc., that purports to be factually accurate and contains no fictional elements: a documentary life of Gandhi.–noun
3. Movies, Television. a documentary film, radio or television program, etc.
A historical documentary recreates an event or a person of the past.
thanks ms. Sue!