Caesarion was born in Egypt on June 23, 47 BC. His mother Cleopatra insisted that he was the son of Julius Caesar. Caesarion was said to have inherited Caesar's looks and manner, but Caesar apparently did not officially acknowledge him. Nevertheless he may have allowed him to use his name. Cleopatra also compared her relationship to her son with the Egyptian goddess Isis and her divine child Horus. The matter became contentious when Caesar's adopted son Octavian came into conflict with Cleopatra. His supporter Gaius Oppius wrote a pamphlet which attempted to prove that Caesar could not have fathered Caesarion. Caesarion spent two of his early years, from 46 to 44 BC, in Rome, where he and his mother were Caesar's guests. Cleopatra hoped that her son would eventually succeed his father as the head of the Roman Republic as well as Egypt. After Caesar's assassination on March 15, 44 BC, Cleopatra and Caesarion returned to Egypt. Caesarion was named co-ruler by his mother on September 2, 44 BC at the age of three, although he was King in name only, with Cleopatra keeping actual authority all to herself.