It was probably based on the translation of the Ancient Greek historian, Plutarch, by Sir Thomas North.
Addition:
Shakespeare used Thomas North's English translation of Plutarch's The Life of Caesar and the Life of Brutus.
Plutarch
Plutarch was more of a historian than a poet.
Shakespeare's play is based on Plutarch's Lives of the Greeks and Romans, which Shakespeare almost certainly took at school.
Shakespeare got much of his information from the writings of Plutarch. But remember, Shakespeare was not a historian, he was a playwright. He used artistic licence to change the characters and their motivations in order to write a good play.
The play is titled "Julius Caesar" because it is about the final days of the Roman king, Julius Caesar.
Plutarch
Plutarch
Julius Caesar, the play by William Shakespeare, is a play, actually.
At his writing desk.
Plutarch was more of a historian than a poet.
Shakespeare's play is based on Plutarch's Lives of the Greeks and Romans, which Shakespeare almost certainly took at school.
Shakespeare got much of his information from the writings of Plutarch. But remember, Shakespeare was not a historian, he was a playwright. He used artistic licence to change the characters and their motivations in order to write a good play.
From a book called Plutarch's Lives
The play is titled "Julius Caesar" because it is about the final days of the Roman king, Julius Caesar.
Brutus' trusted servant in Shakespeare's Julius Caesar.
Octavius was Julius Caesar's nephew and heir.
The only relevance that Julius Caesar had in Elizabethan England was that William Shakespeare wrote the play Julius Caesar. Shakespeare was interested in the story of Caesar.