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.
Augustus
In addition, the credit was given to Augustus for each subsequent Roman military victory after this time, because the majority of Rome's armies were stationed in imperial provinces commanded by Augustus through the legatus who were deputies of the princeps in the provinces. Moreover, if a battle was fought in a Senatorial province, Augustus' proconsular imperium maius allowed him to take command of (or credit for) any major military victory. This meant that Augustus was the only individual able to receive a triumph, a tradition that began with Romulus, Rome's first King and first triumphant general. Lucius Cornelius Balbus was the last man outside Augustus' family to receive this award, in 19 BC. Tiberius, Augustus' eldest stepson by Livia, was the only other general to receive a triumph—for victories in Germania in 7 BC.