Was Caesar really a threat to the Roman Republic? Why or why not?

This is the question that drives Brutus. Julius Caesar did not live long enough for the question to be answered. Brutus holds that the Republic of Rome will be destroyed if an emperor is chosen. Rome will return to the days of tyranny.

The commoners appear to adore Caesar and elevate him above the status of others. The angry Marullus chastises the people for celebrating Caesar’s victory over Pompey:

And do you now put on your best attire?
And do you now cull out a holiday?
And do you now strew flowers in his way
That comes in triumph over Pompey's blood?

However, the plebeians also support Brutus after he assassinates Caesar and claims that Caesar would make the people bondmen and slaves. They then miss the point by declaring, “Let him [Brutus] be Caesar.” In turn, Mark Antony easily turns them against Brutus by making them think that Caesar did not want the throne (he turned down the crown three times). On top of that, Antony proves that Caesar loved the people by reading his generous will.

Brutus even admits, “I have not known when his [Caesar’s] affections sway'd / More than his reason.” Still, he concludes that power could easily corrupt him. Caesar did turn down the crown three times, but Casca described him as doing so reluctantly. Decius tempted Caesar to the senate by telling him that they planned to offer him the crown. Caesar considered himself to be superior others, comparing himself to a fierce lion and to the constant Northern star.

Caesar did pose a threat to the Roman Republic, but one simply does not know what prosperity or harm he would have brought had he lived. What does happen is tumultuous upheaval during the transition period after he is murdered, and, in the end, Brutus’s dream of a Roman Republic is destroyed. In the years to come, Octavius Caesar becomes emperor.