In 39 or 38 BC, Octavian appointed Agrippa governor of Transalpine Gaul, where in 38 BC he put down a rising of the Aquitanians. He also fought the Germanic tribes, becoming the next Roman general to cross the Rhine after Julius Caesar. He was summoned back to Rome by Octavian to assume the consulship for 37 BC. He was well below the usual minimum age of 43, but Octavian had suffered a humiliating naval defeat against Sextus Pompey and needed his friend to oversee the preparations for further warfare. Agrippa refused the offer of a triumph for his exploits in Gaul – on the grounds, says Dio, that he thought it improper to celebrate during a time of trouble for Octavian. Since Sextus Pompeius had command of the sea on the coasts of Italy, Agrippa's first care was to provide a safe harbour for Octavian's ships. He accomplished this by cutting through the strips of land which separated the Lacus Lucrinus from the sea, thus forming an outer harbour, while joining the lake Avernus to the Lucrinus to serve as an inner harbor. The new harbor-complex was named Portus Julius in Octavian's honour. Agrippa was also responsible for technological improvements, including larger ships and an improved form of grappling hook. About this time, he married Caecilia Pomponia Attica, daughter of Cicero's friend Titus Pomponius Atticus.