Julius Caesar was dead, so in that sense he had no literal power. However, his memory held tremendous power. Mark Antony used that power to gain control of Rome.
Brutus and his minions killed Caesar because they feared that he would become a tyrant. If you look closely, you will see that he was not actually doing anything wrong. He was just too loved by the people. They killed him because of not what he was doing, but what they feared he would do. Brutus puts it best.
I know no personal cause to spurn at him,
But for the general. He would be crowned:
How that might change his nature, there’s the
question. (Act 2, Scene 1)
In other words, Caesar has to die because it’s in his nature to be king. Brutus is afraid he is going to become King of Rome.
Caesar has become more of an idea than a person. It is for what he represents that they are killing him. This is part of the reason he was so powerful after he died, as an idea. He was larger than life as a person, so it was easy to use that deification (which was literally true), after he died.
Mark Antony was counting on it. Brutus and company actually played into his hands in a way. As long as Caesar was alive, Antony would always play second string to him. With Caesar dead, Antony had a chance to soar. He used his skills as an orator to show his connection with Caesar to use the people’s love for Caesar in order to gain power. He makes a point to show how emotional he is, for example.
O judgment, thou art fled to brutish beasts,
And men have lost their reason!—Bear with me;
My heart is in the coffin there with Caesar,
And I must pause till it come back to me. (Act 3, Scene 2)
Antony gives an impassioned speech, and turns the people against Brutus and Cassius and the other conspirators by using their love of Caesar, even using his will and body as a prop. By the end of this “eulogy” he has gone from thanking the “honorable” men for letting him talk to setting the angry crowd to torch their houses!
Antony forms a triumvirate with Octavius, the next generation of Caesar. He is Caesar’s grand-nephew (his grandmother was Julius Caesar’s sister), and Caesar’s adopted son. This is political gold. By forming a political alliance with this young man, Antony was taking advantage of his connection with Caesar. He assumed that a seventeen year old would be easy to control. He assumed wrong.
Octavius (usually referred to as Octavian) also used Caesar’s clout to his advantage. He was not as easily manipulated and naïve as Antony expected. Instead he was cunning, calculating, and had political ambitions of his own. They argued almost immediately, and Antony found that ruling with three did not mean that he was going to be in charge with Lepidus and Octavian doing what he said. As you can see in this example, even on the battlefield Octavius did not bow to Antony’s experience or guidance.
Octavius, lead your battle softly on
Upon the left hand of the even field.
Upon the right hand, I; keep thou the left.
Why do you cross me in this exigent?
I do not cross you, but I will do so. (Act 5, Scene 1)
Antony’s plea is telling. He is essentially asking Octavius why he won’t even listen when it is an emergency, on the battlefield. Earlier he reminded Octavius that he has more experience. Octavius admits it, but it’s not enough to make up for Antony’s reputation. Antony has experience, but Octavius knows he can make up for that by surrounding himself with good men.
Students of history (or Antony and Cleopatra) will know that the conflict between Antony and Octavius is only going to get worse. Soon enough he will start calling himself Caesar. He has that right, since he was adopted and given the name in Caesar’s will. The fact that he is so determined to hitch himself to (Julius) Caesar’s star shows the power of that Caesar’s legacy.
Julius Caesar did indeed leave a hard act to follow. In fact, it’s hard to imagine that he of many names, Octavius/Caesar/Augustus, would have accomplished so much without having such high shoulders to stand on. He was indeed a Colossus. Many of his ideas impact us still, and while his death left years of civil war, Augustus eventually brought an empire that created years of peace and influenced the world we live in today.