Gaius Julius Caesar (20 BC – 21 February 4 AD) was a 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 Lucius were raised by their grandfather as his adopted sons and joint-heirs. He experienced 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.

With Marcellus gone, Augustus arranged for the marriage of Agrippa to his daughter Julia the Elder, who was previously the wife of Marcellus. Agrippa was given tribunicia potestas ("the tribunician power") in 18 BC, a power that Augustus received in 23 BC, and later on was exercised only by the emperor and shared with some heirs (Agrippa, Tiberius). The tribunician power allowed him to control the Senate. Agrippa acted as tribune in the Senate to pass important legislation and, though he lacked some of the emperor's power and authority, he was approaching the position of co-regent.

Early life and family

Gaius was born in Rome in 20BC to Marcus Vipsanius Agrippa and Julia the Elder. He was a part of the Julio-Claudian dynasty, and was related to all the Julio-Claudian emperors. On his mother's side, he was the oldest grandson of emperor Augustus. He was the stepson of Tiberius by his mother Julia's marriage to him, and brother in law of Claudius by his sister Agrippina the Elder's marriage to Germanicus. He also was the uncle of Caligula, who was the son of his sister Agrippina. The last emperor of the dynasty was Nero, who was Gaius' great-nephew and the grandson of Germanicus. An annual sacrifice on his birthday was granted in a decree.Cassius Dio, Roman History, LIV.8.5

In 17BC, his brother Lucius was born. Augustus immediately adopted both Gaius and Lucius from their father by a symbolic sale, and named both Gaius and Lucius his (personal) heirs.Cassius Dio, Roman History, LIV.18.1 It is unknown what their father thought of the adoption. Their adoptive father initiated them into administrative life when they were still young, and sent them to the provinces as consuls-elect. Augustus taught Gaius and Lucius how to read, swim, and the other elements of education, taking special pains to train them to imitate his own handwriting, mostly by himself.Suetonius, The Lives of the Twelve Caesars, Life of Augustus, 64 Shortly after their adoption in the summer, Augustus held the fifth-ever Ludi Saeculares ("Secular Games"). The adoption of the boys coupled with the games served to introduce a new era of peace – the Pax Augusta.

That year his family left for the province of Syria, because Agrippa was given command of the eastern provinces with proconsular imperium maius. Four years later, in 13BC, Gaius took part in the Trojan games with the other patrician youths at the dedication of the Theatre of Marcellus. Also in 13BC, Agrippa and Augustus returned to Rome. Augustus sent Agrippa to Pannonia at the end of 13 to suppress a rebellion. Agrippa arrived there that winter (in 12BC), but the Pannonians gave up their plans. Agrippa returned to Campania in Italy, where he fell ill and died soon after.Cassius Dio, Roman History, LIV.28.1–2 The death of Gaius' father made succession a pressing issue. The aurei and denarii issued in 13–12BC made clear the Emperor's dynastic plans for Gaius and Lucius.

The luxurious rural villa-estate at Ossaia near Cortona was owned by Gaius and Lucius Caesar.The Imperial “Villa” at Ossaia (Arezzo, Italy): Preliminary Data on the Territory of Roman Cortona, Helena Fracchia et al. Echos du monde classique: Classical views, University of Toronto Press, Volume XL, n.s. 15, Number 1, 1996, pp. 157-200

Their father was no longer available to assume the reins of power if the Emperor were to die, and Augustus had to make it clear who his intended heirs were in case anything should happen. To learn about military affairs, he accompanied Tiberius in his campaign against the Sicambri in 8BC. The year before, Tiberius' brother Drusus the Elder died on his way back from a campaign across the Rhine. Tiberius was given command of Germania, and waged two campaigns across the Rhine in 8BC and 7BC. He marched his army between the Elbe and the Rhine, and met little resistance, except from the Sicambri. Tiberius came close to exterminating the Sicambri, and had those who survived transported to the Roman side of the Rhine, where they could be watched more closely.

Career

Early political career

Gaius was designatus by the Comitia Centuriata in 6BC with the intention that he should assume the consulship in his twentieth year. The next year, Augustus made him a pontifex, and granted him the right to attend Senate meetings, behold spectacles, and to be present at banquets with senators.Cassius Dio, Roman History, LV.9 Roman support for the young prince soon spread through Italy; statues and inscriptions were set up in every district to commemorate the fact that he had been nominated as a consul at an unprecedented age of fourteen.;

The following year (5BC), when he attained military age, he assumed the toga virilis, and was introduced by Augustus to the Senate, who declared him as princeps iuventutis ("leader of the youth") and sevir turmae (commander of a cavalry division). Having been designated consul, he was allowed to give his opinion to the senate. Lucius, three years his junior, was granted the same honours after the appropriate interval had elapsed.

Herodian succession

Following the death of King Herod of Judaea in 4BC,The death of Herod was on 1 January BC according to some scholars. See Andrew Steinmann, From Abraham to Paul: A Biblical Chronology. (St. Louis, MO: Concordia Pub. House, 2011), Print. pp. 219-256. W.E. Filmer, "The Chronology of the Reign of Herod the Great". The Journal of Theological Studies, 1966. 17(2): p. 283-298. Finegan, Jack. Handbook of Biblical Chronology: Principles of Time Reckoning in the Ancient World and Problems of Chronology in the Bible. Peabody, MA: Hendrickson, 1998, 2015. pp. 238-279. his sons Antipas and Archelaus both came to Rome with their own copy of Herod's will to plead their case as to why they each deserved to inherit their father's kingdom. Augustus, as usual, declined the sole responsibility of the decision. He convened a council of senators, among whom he included Gaius. The council decided to ratify the will brought by Archelaus, which included a large bequest to Augustus and his wife Livia.Josephus, Antiquities of the Jews, XVII.9.5 The cities of Judaea rose in revolt after the procurator, Sabinus, garrisoned Syria Palaestina to guard the tens of millions of sesterces promised to the Emperor.Josephus, Antiquities of the Jews, XVII.10.2–10 The governor of Syria, Varus, was forced to bring in the legions from Syria to restore order.

At the same time, King Phraates IV of Parthia had seized Armenia with the help of Armenian nationalists, and expelled Tigranes IV, the king installed by Rome.Velleius Paterculus, II.100 Historian Ferrero speculates that Phraates may have been hoping to use Armenia as a bargaining chip to secure the release of his sons who were held captive by the Romans. Roman supremacy in Asia depended on its possession of Armenia as a protectorate. Before Rome could deal with the Parthians in Armenia, it would first need to make its Syrian legions available, which were still tied down in Palestine. In order to free up the legions there, the Kingdom of Judaea was divided among the sons of Herod the Great. One half remained under Archelaus, while the other half was subdivided between his brothers, Antipas and Philip. This served to restore stability to the region, whilst keeping Judaea from becoming powerful. Having settled matters in Judaea, the Emperor decided to deploy an army to Armenia to re-establish its status as a Roman protectorate and to show the eastern world that Rome held dominion over all land as far as the Euphrates.

Command in Asia

Departure

Due to his advanced age, Augustus was unable to travel to the east himself. There were few to whom the Emperor could entrust matters in the east, but he was confident in Gaius. Gaius made a good choice because his presence represented that of the imperial family – all orders, promises, or threats coming from him were as valid as if they came from the Emperor himself. Nonetheless, he was only eighteen, and therefore too young for the conduct of important business.

Before leaving for the east, he and his brother Lucius were given the authority to consecrate buildings, and they did, with their management of the games held to celebrate the dedication of the Temple of Mars Ultor (1 August 2BC). His youngest brother, Postumus, participated in the Trojan game with the rest of the equestrian youth. 260 lions were slaughtered in the Circus Maximus, there was gladiatorial combat, a naval battle between the "Persians" and the "Athenians", and 36 crocodiles were slaughtered in the Circus Flaminius.Cassius Dio reports that, after the games, Gaius was given command of the legions on the Ister (Danube), and that he did not take part in actions as he was there to learn (Dio, LV.10).Cassius Dio, Roman History, LV.10

Friends of Augustus had hoped that he would abandon his plan of sending Gaius to the east but, faced with increasing troubles there, he persisted with the plan and dispatched Gaius to Syria at the beginning of 1BC. The Emperor entrusted Gaius with proconsular authority and had him marry his second cousin Livilla, the daughter of Drusus the Elder and Antonia Minor.

Due to Gaius' youth and inexperience, the Emperor had advisors go with him. Among his entourage to the east were: Marcus Lollius as adiutor ("helper"),Suetonius, The Lives of the Twelve Caesars, "Tiberius", 12 Publius Sulpicius Quirinus as rector ("guide"),Tacitus, The Annals, III.48 the future historian Velleius Paterculus,Velleius Paterculus, II.101 Lucius Domitius Ahenobarbus (grandfather of Nero),Suetonius, The Lives of the Twelve Caesars, "Nero", 5 Juba II of Numidia, and future praetorian prefect Sejanus.Tacitus, The Annals, IV.1