History of the Constitution of the Roman Republic
The history of the Constitution of the Roman Republic is a study of the ancient Roman Republic that traces the progression of Roman political development from the founding of the Roman Republic in 509 BC until the founding of the Roman Empire in 27 BC. The constitutional history of the Roman Republic can be divided into five phases. The first phase began with the revolution which overthrew the Roman Kingdom in 509 BC, and the final phase ended with the revolution which overthrew the Roman Republic, and thus created the Roman Empire, in 27 BC. Throughout the history of the republic, the constitutional evolution was driven by the struggle between the aristocracy and the ordinary citizens.
History of the Roman Empire
As a matter of historical convention, the late Roman Empire emerged from the Roman Principate (the early Roman Empire), with the accession of Diocletian in 284, his reign marking the beginning of the Dominate, or Late Roman Empire. It may begin with the commencement of the reign of Diocletian in AD 284, following the Third Century Crisis of AD 235–284, and to end in the west with the collapse of the Western Empire in AD 476, while in the east its end is disputed, as either occurring at the close of the reign of Justinian I (AD 565) or of Heraclius (AD 641).