In Shakespeare's Romeo and Juliet, the Prologue first introduces the long-standing feud, where fighting has recently been renewed. The Chorus tells the audience that the families are very similar, yet they are causing unrest throughout Verona with their warfare.
Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean. (Prologue, lines 1-4)
In Act One, scene one, there is mayhem and bloodshed taking place in the streets of Verona. First the audience meets Sampson and Gregory, servants in the Capulet household. As they walk, they discuss how they might get around the law that forbids fighting. A law has been established not just to stop the fighting between the Montagues and the Capulets, but to keep the peace for other members of the town, while also protecting them.
Enter Abram and Balthasar, servingmen of the Montagues. The Capulet servants want to incite violence, and make sure the blame falls on the Montagues. Benvolio arrives and tries to stop them. Tybalt, always ready for a fight, starts to blame Benvolio for starting the battle because his sword is already out.
What, art thou drawn among these heartless hinds?
Turn thee, Benvolio! look upon thy death.
I do but keep the peace. Put up thy sword,
Or manage it to part these men with me.
What, drawn, and talk of peace? I hate the word
As I hate hell, all Montagues, and thee.
Have at thee, coward! (I.i.61-67)
An officer of Verona enters and armed citizens. The citizens are so disgusted with the constant violence that they join the fray, shouting for the destruction of both Montagues and Capulets. Old Capulet enters, calling for a sword—while his wife says he really needs a crutch. Capulet wants to go after the Montagues. Then the Montagues enter and Montague also wants to fight, but his wife holds her husband back.
At this point, Prince Escalus enters, and he stops the fighting. First he calls the brawling men "beasts," and tells them to stop fighting. When they don't listen, he tells them to throw down their weapons or they will be tortured—that they had better listen to him as he is very angry.
On pain of torture, from those bloody hands
Throw your mistempered weapons to the ground
And hear the sentence of your moved Prince. (lines 82-84)
The Prince says that three recent fights have broken out and disturbed the piece because of the Capulets and the Montagues:
Three civil brawls, bred of an airy* word
By thee, old Capulet, and Montague,
Have thrice disturb'd the quiet of our streets... (85-87)
("...Bred of an airy word" means "started by meaningless comment.")
Escalus says that if fighting breaks out again, those involved will pay with their lives. (This is foreshadowing.)
If ever you disturb our streets again,
Your lives shall pay the forfeit of the peace. (92-93)
The Prince is clear that the fighting has been going on for some time—too long; he clearly blames the Capulets and Montagues who have stirred up the town: even the elderly are fighting with rusted swords. In no uncertain terms, the Prince expects to be obeyed, by threat of death for disobeying him.
This is only the beginning of scene one, but it is clear between the Prologue and the first part of this scene that the fighting between the families has been going on for sometime: this unrest will greatly impact Romeo and Juliet.