Julius Caesar was the most powerful leader in ancient Rome. He had won great battles and was loved by many Roman citizens. But on March 15, 44 BC, a group of Roman senators attacked him. This date was called the Ides of March on the Roman calendar. The senators were worried that Caesar wanted to become king. Rome had been a republic for almost five hundred years. In a republic, leaders are chosen by the people. The senators feared Caesar would end this system and rule alone. A group of about sixty senators made a secret plan. They were led by two men named Brutus and Cassius. On that morning, they surrounded Caesar in the Senate building. According to ancient writers, Caesar was shocked to see Brutus among his attackers. He had considered Brutus a close friend. Caesar's death did not save the republic as the senators had hoped. Instead, it led to years of civil war. Caesar's adopted son, Octavian, eventually became Rome's first emperor. The senators had tried to protect the republic, but their actions destroyed it instead.