This is an interesting question with regard to why the play was not called Marcus Brutus. Shakespeare’s Julius Caesar has long been controversial. The title of the play becomes provocative since Caesar dies in the first scene of Act III. Undoubtedly, Shakespeare debated about his hero and the title of the play.
Marcus Brutus takes the role of the protagonist from Act I, Scene ii and to his death at the end of the drama. He is courted by Cassius to join the conspiracy because his prestige will add to the validity of the assassination. Once, Brutus decides to take part in the murder of Caesar than he asserts himself and becomes the leader of the conspirators.
As the leader, Brutus makes many poor decisions that are based on his arrogance and lack of experience. He overrides the more experienced and insightful Cassius at every turn; consequently, his influence becomes the most important aspect of the play especially after Caesar dies.
The most telling lines in the play that Shakespeare provided for the audience to understand Brutus’s importance comes from his arch rival, Marc Antony:
This was the noblest Roman of them all.
All the conspirators, save only he
Did that they did in envy of great Caesar;
He only, in a general honest thought
And common good to all, made one of them.
His life was gentle, and the elements
So mix'd in him that Nature might stand up
And say to all the world, “This was a man!”
This sounds like a vote for calling the drama Marcus Brutus. It is not. Julius Caesar was the greatest general of his time. His victories and theories about battle strategy were legendary. In addition, he kept the Roman coffers filled with gold and other contraband including slaves.
Caesar’s arrogance kept him in trouble with the senators who were jealous of his power. He did have a desire to be king of the Roman empire. No one knows for sure how good a ruler he would have been; yet, it is his name that was the more recognized of his time and of Shakespeare’s as well. The assassination of Julius Caesar is the subject of the play even after he is killed. Everything happens because of Caesar’s death.