Cassius instigates the plot to assassinate Caesar. William Shakespeare’s drama The Tragedy of Julius Caesar is based on historical facts from 44 B.C. In actuality for dramatic license, Shakespeare combines the number of senators to keep the play from being deluged with assassins.
There is no question that Cassius did not want Caesar to be the monarch of Rome holding supreme power. Cassius was not alone; however, his reasons were more personal than some senators. Brutus wanted Caesar to not rule Rome alone in fear that he would become too powerful.
In several places, Cassius gives his reasons for wanting Caesar killed. His testimony is clear, and there is no doubt that he was sure his cause was just.
… but, for my single self,
I had as lief not be as live to be
In awe of such a thing as I myself.
Act 1, Scene ii—Cassius states that he does not know what other men feel but he would rather not live if someone who is his equal is so revered that Cassius would have to venerate him.
In the same scene:
When could they say till now that talk'd of Rome
That her wide walls encompass'd but one man?
Cassius sardonically states that there has never been only one man who could rule Rome because he was so great. Caesar is no better than Cassius or Brutus. In fact, Cassius calls Caesar womanly. He is appalled that Caesar is so well-beloved that the senate would make him the ruler for life.
Cassius finalizes his conversation with Brutus with this statement:
Caesar's ambition shall be glanced at.
For we will shake him, or worse days endure.
Cassius lets the audience in this aside that the plot has already been formulated because he alerts Brutus that Caesar will be taken care of or Rome will suffer for it.
Later in Act I, Cassius along with Cinna meets Casca in the streets of Rome. It is March 14, 44 B.C., and the day and night have had many portents and signs leading toward a significant event. Cassius gives the interpretation that the Gods support his plan to assassinate Caesar through the storms and unusual events. He also intends on meeting with the other assassins to formulate the final plans and then go to Brutus’ house to be sure that he will support the plot.
There is no doubt that Cassius fully supported the assassination plan and was the primary leader.