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.
History of the Roman Constitution
By 48 BC, after having defeated the last of his major enemies, Julius Caesar wanted to ensure that his control over the government was undisputed. He assumed these powers by increasing his own authority, and by decreasing the authority of Rome's other political institutions. Caesar held the office of Roman Dictator, and alternated between the Consulship (the chief-magistracy) and the Proconsulship (in effect, a military governorship). In 48 BC, Caesar was given the powers of a Plebeian Tribune, which made his person sacrosanct, gave him the power to veto the Senate, and allowed him to dominate the legislative process. After Caesar was assassinated in 44 BC, Mark Antony formed an alliance with Caesar's adopted son and great-nephew, Gaius Octavian. Along with Marcus Aemilius Lepidus, they formed an alliance known as the Second Triumvirate, and held powers that were nearly identical to the powers that Caesar had held under his constitution. While the conspirators who had assassinated Caesar were defeated at the Battle of Philippi in 42 BC, the peace that resulted was only temporary. Antony and Octavian fought against each other in one last battle in 31 BC. Antony was defeated, and in 30 BC he committed suicide. In 29 BC, Octavian returned to Rome as the unchallenged master of the state. The reign of Octavian, whom history remembers as Augustus, the first Roman Emperor, marked the dividing line between the Roman Republic and the Roman Empire. By the time this process was complete, Rome had completed its transition from a city-state with a network of dependencies, to the capital of an empire.