Final answer:
The quarrel between the Capulets and Montagues provides the central conflict in 'Romeo and Juliet,' which is essential for the development of the plot and leads directly to the tragic climax where both protagonists die as a consequence of their families' feud.
Step-by-step explanation:
The quarrel between the Capulets and Montagues in Romeo and Juliet plays a critical role in setting up the central conflict of the play. This ongoing feud is the cornerstone of the play's dramatic tension and propels the plot forward by preventing the two young lovers, Romeo and Juliet, from being together. This animosity between their families leads to various secret schemes including their secret marriage and ultimately results in the tragic climax of the play, where the inability to reconcile this conflict results in the deaths of both protagonists.
The climax occurs when Juliet, who has taken a sleeping potion to feign death, is visited by an unaware Romeo at her tomb. Believing Juliet to be dead, Romeo takes his own life. When Juliet awakens and sees that Romeo has died, she is unable to imagine living without him and uses his dagger to end her life as well. This series of events is fueled by the initial conflict stemming from their families' hatred, which is portrayed as the inciting incident at the very beginning and is the source of the play's tragic unfolding.