At the age of eighteen in 44 BC, Octavius was nominated "magister equitum" by his granduncle, Gaius Julius Caesar, who held the office of dictator. On the Ides of March, Caesar was assassinated, without legitimate children; but in his will he adopted his nephew, who then became , "Gaius Julius Caesar Octavianus, son of Gaius". Thus far, his name follows the Republican model, becoming that of his adoptive father, followed by his original nomen in the form of an agnomen.