Characteristically, Shakespeare does not attempt to represent a great battle on his small stage. Instead he shows various men in armor speaking to each other. In Act V, Scene 1, Brutus and Cassius are exchanging some final words before going into battle. Brutus tells Cassius that he will not under any circumstances allow himself to become a prisoner. He regards the coming battle as decisive and conclusive. When he says, "But this same day / Must end that work the ides of March begun," he is, of course, referring to the assassination of Julius Caesar which occurred on the ides (15th day) of March and is dramatized in Act III, Scene 1. Brutus is implying that everything that has happened up to that moment was set in motion as an unbreakable chain of cause and effect by Caesar's assassination. He is being philosophical--willing to accept whatever fate has in store. Act V, Scene 1 ends with a short speech by Brutus which not only shows his philosophical character but reminds many viewers and readers of what they themselves have thought and felt when about to engage in some affair of great personal importance.
O that a man might know
The end of this day's business ere it come!
But it sufficeth that the day will end,
And then the end is known.
Brutus is implying here that the end of this day's business is already foreordained but unknowable to mortals. It is a very intriguing thought. Is everything that will ever happen in our lives already predetermined? The Soothsayer who told Caesar to beware the ides of March seemed to have that belief. We in the audience have a sort of supernatural intelligence. We know that Caesar will be assassinated. We know that Brutus and Cassius will lose the Battle of Philippi.
It is noteworthy that most of the action occurs offstage and that Shakespeare concentrates on dialogue.