Lucius Julius Caesar was a grandson of Augustus, the first Roman emperor. The son of Marcus Vipsanius Agrippa and Julia the Elder, Augustus' only daughter, Lucius was adopted by his grandfather along with his older brother, Gaius Caesar. As the emperor's adopted sons and joint-heirs to the Roman Empire, Lucius and Gaius had promising political and military careers. However, Lucius died of a sudden illness on 20 August 2 AD, in Massilia, Gaul, while traveling to meet the Roman army in Hispania. His brother Gaius also died at a relatively young age on 21 February 4 AD. The untimely loss of both heirs compelled Augustus to redraw the line of succession by adopting Lucius' younger brother, Agrippa Postumus as well as his stepson, Tiberius on 26 June 4 AD.