Remaining political career
In 19/18 BC, Augustus appointed Lollius as a Roman governor again, this time to the province of Macedonia. During his governorship, Lollius defeated a Thracian tribe called the Bersi, as known from a fragmentary inscription found in Philippi, Greece.
In 17/16 BC Lollius was appointed by Augustus as governor of Gaul. During his governorship, he was responsible for several legions who guarded the Rhine river. His legions were defeated by the Germanic tribes—the Sicambri, Tencteri and Usipetes—that had crossed the Rhine. The military defeat that Lollius suffered, known as the clades Lolliana, is coupled by Suetonius with the disaster of Publius Quinctilius Varus, Suetonius called it disgraceful rather than dangerous. In 15 BC Augustus dispatched his step-son Tiberius to rectify the situation and to regain the captured standard of the Legio V Macedonica. On the arrival of Tiberius, the Germanic tribes retired beyond the Rhine. The Romans then proceeded to conquer Rhetia and the Alpine region. Although the political and military career of Lollius suffered, and he was never again given command of an army, he remained on friendly terms with Augustus.
The Horrea Lolliana was either built by Lollius or his son of the same name. It is known from the inscriptions that refer to them, and also from their plan in the Severan Marble Plan of Rome. It seems that the family of Lollius had extensive trade connections, and his family's name is found among the Italian merchants on the Greek island of Delos in the Hellenistic period.
Lollius in 2/1 BC was appointed by Augustus as a tutor to his adopted son and grandson Gaius Caesar on his mission to the Roman East and to learn about government. Among the officers who escorted them were the historian Marcus Velleius Paterculus, Roman Senator Publius Sulpicius Quirinius, and the future Praetorian prefect Lucius Aelius Sejanus.
When all the men arrived in the Roman East, embassies were sent to Lollius, instead of Gaius Caesar, whom they completely ignored. Lollius' relations with Gaius Caesar started to deteriorate when they visited Tiberius, who was living in voluntary exile on the Greek island of Rhodes. Lollius had poisoned Gaius Caesar's mind against Tiberius, whom Lollius had hated since 16 BC. Gaius Caesar seems to have insulted his uncle Tiberius, and Lollius was held responsible for the incident.
As Lollius and Gaius Caesar continued their tour of the Roman East, they started to quarrel. Lollius fell out of favor with Gaius Caesar, as he was accused of receiving bribes from the Parthian King, Phraates. As Gaius Caesar denounced Lollius to Augustus, Lollius, depending on the source, either poisoned himself or committed suicide in an unspecified manner to avoid punishment, or else died from natural causes.
