The guards are shown to be uneasy. In part they may fear the 24-hour per day preparations against Fortinbras that Horatio tells of in 1.1. Even though there is no evidence that Francisco (the guard going OFF duty in 1.1) knows about the ghost, he still says he is "sick at heart"(1.1.9). Bernardo and Marcellus have already seen the ghost as the play opens. It is noteworthy that they do not tell anyone official--such as the King or Polonius--but go to the known friend of Prince Hamlet. Marcellus and Bernardo accompany Horatio as he tells the prince of the apparition in 1.2. They do not object when Hamlet asks them to keep their news quiet in 1.2, and they are ready to swear to silence after Hamlet has talked with the ghost.

In Kenneth Branagh's 1996 film, Horatio (Nicholas Ferrell), Marcellus (Jack Lemmon), and Barnardo (Ian McElhinney), left to right, see the Ghost. Rolf Konow & Peter Mountain