Angrivarii
The wars began in the last years of the reign of Augustus, first emperor of Rome. Augustus died an old but respected man in the year 14 and was celebrated with much pomp and splendor. He left a document to be read to the senate posthumously, expressly forbidding extension of the empire beyond the Rhine. News of the will was welcomed by the Germans, thinking it gave them a free hand in the region. Germanicus found it necessary to pacify the border, which he did by a combination of scorched earth raids and offers of alliance with Rome - in short, stick and carrot. These raids also kept the army of the lower Rhine distracted from the possibility of mutiny, which had broken out on Augustus's death and only been quelled by concessions and executions.
Roman emperor
In 27 BC, Octavian appeared before the Senate and offered to retire from active politics and government; the Senate not only requested he remain, but increased his powers and made them lifelong, awarding him the title of Augustus (the elevated or divine one, somewhat less than a god but approaching divinity). Augustus stayed in office until his death; the sheer breadth of his superior powers as "princeps" and permanent "imperator" of Rome's armies guaranteed the peaceful continuation of what nominally remained a republic. His "restoration" of powers to the Senate and the people of Rome was a demonstration of his "auctoritas" and pious respect for tradition.