Julius CaesarCae·sar, Ju·li·us /ˈsiːzə, ˈdʒuːliəs $ -zər/ (100–44 BC) a Roman politician, military leader, and writer, who took control of the government of Rome and changed it from a republic to an empire, making himself the first Roman emperor. For this reason, he was murdered by Brutus and Cassius, and Shakespeare wrote a play called Julius Caesar which describes these events. He is also known as the first Roman leader to attack Britain.