A docudrama (or documentary drama) is a genre of radio and television programming, feature film, and staged theatre, which features dramatized re-enactments of actual events. On stage, it is sometimes known as documentary theatre.
In the core elements of its story a docudrama strives to adhere to known historical facts, while allowing a greater or lesser degree of dramatic license in peripheral details, and where there are gaps in the historical record. Dialogue may include the actual words of real-life persons, as recorded in historical documents. Docudrama producers sometimes choose to film their reconstructed events in the actual locations in which the historical events occurred.
Game Zero Definition of theatre of fact.
McGraw-Hill Useful definition of documentary drama.
Robert Hubbard Very good description of what documentary drama entails (scroll down).