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 (Principate)
A far more important development was the "Second Settlement" of 23 BC, when Caesar Augustus accepted "tribunicia potestas" for life and "imperium maius proconsulare". Two further developments concluded the establishment of the Imperial dignity: Caesar Augustus accepted "imperium consulare" on an "ad personam" basis in 19 BC and was elected "pontifex maximus" in 13 BC. Thus the Imperial dignity was fully established as the extraordinary concentration of ordinary powers and immunities."Caesar Augustuss third wife Livia Drusilla (subsequently "Julia Augusta") had previously borne two children by her first husband, Tiberius Claudius Nero: Tiberius and Drusus. Tiberius's second wife was Julia the Elder, Marcus Agrippa's widow (his first wife had been Vipsania, Agrippa's daughter by his first marriage); Caesar Augustus adopted Tiberius on June 26, 4, whereupon Tiberius himself adopted his brother Drusus's son by Mark Antony's daughter who was also Augustus' niece, Germanicus Julius Caesar. Germanicus married Vipsania Agrippina, Agrippa's daughter by Julia and Tiberius's stepdaughter, and had by her one surviving son, Gaius "Caligula" ("Little Boots"), and a daughter, Julia Agrippina, whose third husband was Germanicus's brother by blood, Claudius (she was his fourth wife); Agrippina had already borne a son, Lucius, whom Claudius adopted under the name Nero"' in 40; Nero married Claudius's daughter Claudia Octavia in 53.