The effect of Caesar's assassination in Act 3 of the play is intentionally anticlimactic. Here is the description of the action in full:
This is after a buildup that consumes almost the entirety of the first two acts. Shakespeare wanted to make his audience expect the actual assassination to be the high point of the play, but he knew that such action on a stage always looks awkward and unrealistic. He wanted the high point of his play to come in the form of emotionally moving iambic pentameter in the funeral speech made by Marc Antony. The audience feels a let down when the assassination finally occurs after all the plotting and all the signs and wonders, but then they are caught up in what is possibly the greatest passage of poetry Shakespeare ever wrote in a play. By disappointing the audience in the first place, Shakespeare makes the thrill of Antony's apparently apontaneous poetry that much stronger. Antony not only moves the Roman mob to mutiny, but he moves Shakespeare's theater audience to take a new interest in the play. The audience has been empathizing with Brutus and Cassius up to this point, but afterwards most of them will be empathizing with Antony and Octavius--which was exactly what had taken place some sixteen-hundred years earlier.
The answer to the question "What is the dramatic effect of Caesar's death?" is that the effect is one of disappointment. The viewers must feel that the play is just about ended because Caesar is dead, but then they realize that a whole new chain of events is just starting.
The conspiracy against Julius Caesar in William Shakespeare’s play is, as is often the case when a small clique conspires without the knowledge or consent of the larger population, party or faction, to implement a radical plan of action designed to fundamentally transform the status quo. Conspiracies, especially when they involve the planned assassination of a great leader, are inherently dramatic. In the hands of history’s greatest playwright, that drama is intensified. That a group of scheming politicians plotted Caesar’s demise out of concern for the latter’s growing ambitions and determination to rule as king is not overly dramatic; that Caesar’s close friend and confidante, Marcus Brutus, should participate in his assassination provides Julius Caesar with its greatest drama. Brutus, alone among the conspirators, acted not out envy regarding the public’s growing adulation of Caesar and out of fear for the personal implications of Caesar’s rise in power, but out of entirely meritorious and honorable intentions. Caesar’s death in Act III, Scene I, is followed by an immediate rupture among the conspirators, with Brutus concerned that his motivations for participating in the plot not be misconstrued. In appealing to Marc Antony, who fears for his own life, Brutus makes clear that his motivations were honorable and that he acted with great trepidation:
And, so that all of Rome would know of the motivations of the respective conspirators, Brutus makes a point of separating himself from Cassius, the most vocal of the assassins:
“Cassius, go you into the other street,
And part the numbers.
Those that will hear me speak, let 'em stay here;
Those that will follow Cassius, go with him;
And public reasons shall be rendered
Of Caesar's death.”
Brutus, history’s identification of him as a duplicitous traitor to his friend notwithstanding, is alone among the conspirators for his noble motivations. These motivations would find their greatest voice in his comments in his eulogy for the fallen Caesar:
“If there be any in this assembly, any dear friend of
Caesar's, to him I say, that Brutus' love to Caesar
was no less than his. If then that friend demand
why Brutus rose against Caesar, this is my answer:
--Not that I loved Caesar less, but that I loved
These are not intended by Shakespeare to represent the kind of platitudinous and superficial remarks we’ve come to expect today. Shakespeare takes every opportunity to reinforce the notion of Brutus as an honorable man. Following Brutus’s self-inflicted fatal wound by impaling himself on a sword held by Strato, Marc Antony, reflecting upon Brutus’s legacy, describes the now-dead Brutus as “the noblest Roman of them all.” That this passage marks the end of Julius Caesar speaks to the importance Shakespeare attributed to Brutus’ role in Caesar’s assassination. The greatest drama in Julius Caesar is not Caesar’s death, which occurs half-way through the play, but in Brutus’ struggle to reconcile his participation in Caesar’s assassination with what he knows to be his greater humanity.
Caesar's death is dramatic because it marks a huge turning point in Julius Caesar by William Shakepeare. After his death, the big question arises on who is the villian and the hero. Whether or not Caesar's death is justified or not. Also, who will rule Rome, these are all questions that occur when Caesar dies. Also, it sparks a civil war over who rules Rome.