Overview
Gaius Caesar (; 20 BC – 21 February 4 AD) was the grandson and heir to the throne of Roman emperor Augustus, alongside his younger brother Lucius Caesar. Although he was born to Marcus Vipsanius Agrippa and Julia, Augustus' only daughter, Gaius and his younger brother, Lucius Caesar, were raised by their grandfather as his adopted sons and joint-heirs to the empire. He would experience an accelerated political career befitting a member of the Julio-Claudian dynasty, with the Roman Senate allowing him to advance his career without first holding a quaestorship or praetorship, offices that ordinary senators were required to hold as part of the cursus honorum.
In 1 BC, Gaius was given command of the eastern provinces, after which he concluded a peace treaty with King Phraates V of Parthia on an island in the Euphrates. Shortly afterwards, he was appointed to the office of consul for the following year, 1 AD. The year after Gaius' consulship, Lucius died at Massilia in the month of August. Approximately eighteen months later, Gaius died of an illness in Lycia. He was married to his second cousin Livilla but they did not have children. In 4 AD, following the deaths of Gaius and Lucius, Augustus adopted his stepson, Tiberius, as well as his sole-surviving grandson, Agrippa Postumus.
Background
Marcus Vipsanius Agrippa was an early supporter of Augustus (then "Octavius") during the Final War of the Roman Republic that ensued as a result of the assassination of Julius Caesar in 44 BC. He was a key general in Augustus' armies, commanding troops in pivotal battles against Mark Antony and Sextus Pompeius. From early on, Agrippa was trusted to handle affairs in the eastern provinces and was even given the signet ring of Augustus, who was seemingly on his deathbed in 23 BC, a sign that he would become princeps were Augustus to die. However, as soon as he recovered, Augustus began to show he favored his nephew, Marcus Claudius Marcellus, then just 19. However, Marcellus died of an illness that had spread throughout the city of Rome that year.
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