In
21 BC, having now reached the age of 18, Julia married
Marcus Vipsanius Agrippa, a man from a modest family who had risen to become Augustus' most trusted general and friend. This step is said to have been taken partly on the advice of Maecenas, who in counselling him upon these very matters remarked: "You have made him so great that he must either become your son-in-law or be slain" . Since Agrippa was nearly 25 years older than she, it was a typical arranged marriage, with Julia functioning as a pawn in her father's dynastic plans. There is from this period the report of an infidelity with one Sempronius Gracchus, with whom Julia allegedly had a lasting
liaison (
Tacitus describes him as "a persistent paramour") . This was the first of a series of alleged adulteries. According to Suetonius, Julia's marital status did not prevent her from conceiving a passion for Augustus' stepson
Tiberius, so it was widely rumoured .
The newly-weds lived in a villa in Rome that was excavated near the modern
Farnesina in
Trastevere. Agrippa and Julia's marriage resulted in five children:
Gaius Caesar, Vipsania Julia Agrippina (also known as
Julia the Younger), Lucius Caesar, Julia Vipsania Agrippina or
Agrippina Major (mother of Emperor
Caligula), and
Agrippa Postumus (a posthumous son). From June
20 BC to the spring of
18 BC, Agrippa was governor of
Gaul, and it is likely that Julia followed him to the country on the other side of the Alps. Shortly after their arrival, their first child Gaius was born, and in
19 BC, Julia gave birth to Vipsania Julia. After their return to Italy, a third child followed: a son named Lucius.
Nicolaus and
Josephus mentions that during Julia's marriage to Agrippa, she was travelling to meet Agrippa where he was campaigning, was caught up in a flash flood in
Ilium (Troy), and almost drowned . Agrippa was furious, and in his anger he fined the locals 100,000 drachmae. The fine was a heavy blow but no one would face Agrippa for an appeal. It was only once
Herod, king of Judaea, went to Agrippa to receive pardon that he withdrew the fine. In the spring of
16 BC, Agrippa and Julia started a tour through the eastern provinces, where they visited
Herod. In October
14 BC, the couple travelled to
Athens, where Julia gave birth to her fourth child, Agrippina. Augustus, who took care of their education personally, adopted the boys Lucius and Gaius Caesar after their father's death in
12 BC.
After the winter, the family returned to
Italy. Julia quickly became pregnant again, but her husband died suddenly in March
12 BC in
Campania at the age of 51. He was buried in the Mausoleum of Augustus. Julia named the
posthumous son Marcus in his honor. He was to be known as
Agrippa Postumus. Immediately after the boy was born, and while Julia was still in mourning, Augustus had her betrothed and then remarried to
Tiberius, her stepbrother.