In the first scene of the first act of William Shakespeare's Hamlet, Horatio gives the audience some historical background information. He recalls the rivalry between the late King Hamlet of Denmark and Fortinbras, the king of Norway. Fortinbras challenged Hamlet to a fight, during which Hamlet killed Fortinbras. The two had agreed before the battle that the winner would assume the other's property. As per the stipulations of legal documents, all of Fortinbras's land and territories were surrendered to Hamlet.
Fortinbras's son, who shares the same name as his father, gathered a large group of criminals and thugs and is planning to enlist their help in reclaiming his late father's land. For this reason, guards are stationed outside Elsinore Castle each night to keep watch for the young Fortinbras and his army.
Horatio notes that a series of strange, ominous events occurred prior to the assassination of the Roman Emperor Julius Caesar. Corpses rose from the dead and ran wild in the streets; stars shot through the sky; strange signs appeared on the sun; and there was a lunar eclipse. Horatio believes that the appearance of King Hamlet's ghost, as well as other mysterious occurrences, are portents of horrible things to come, just as ominous events preceded the death of Julius Caesar.