Given name: Gaius Vipsanius Agrippa

oldest son of Marcus Agrippa,
grandson & heir apparent of Augustus,
cousin of Claudius.

When Gaius' father died (12 BCE), his grandfather adopted him & his younger brother Lucius. His name was changed to Gaius Julius Caesar Vipsanianus & he was prepared to become Augustus' successor, holding a series of public offices despite his youth. At age 21 (1 CE) he was named consul of Rome, but was unable to serve since he was on a military campaign in the East. The next year he was made governor of Syria. Before he could return to Rome, he was fatally wounded while fighting in Armenia. Gaius' untimely death forced Augustus to name his stepson, Tiberius, his successor.

References: Suetonius, Twelve Caesars: Augustus 64-65.
                  Cassius Dio, Roman History 54.8;  55.9-12.

Other resources on line:

• Gaius Caesar - article in Wikipedia's growing web.
• Gaius Caesar - Jona Lendering lists basic facts [Livius: Articles in Ancient History]