The
Roman Empire was the post-
Republican period of the
ancient Roman civilization, characterised by an
autocratic form of government and large territorial holdings in Europe and around the Mediterranean.
The term is used to describe the Roman state during and after the time of the first
emperor,
Augustus.
The 500-year-old
Roman Republic, which preceded it, had been weakened and
subverted through several
civil wars.
Several events are commonly proposed to mark the transition from Republic to Empire, including
Julius Caesar's appointment as perpetual
dictator (44 BC), the
Battle of Actium (
2 September 31 BC), and the Roman Senate's granting to
Octavian the
honorific Augustus (
4 January 27 BC).
Roman expansion began in the days of the Republic, but reached its zenith under Emperor
Trajan. At this territorial peak, the Roman Empire controlled approximately
6.5 million km
2 of land surface. Because of the Empire's vast extent and long endurance, the institutions and culture of Rome had a profound and lasting influence on the development of language, religion, architecture, philosophy, law, and forms of government in the territory it governed, particularly Europe, and by means of European expansionism throughout the modern world.
In the late 3rd century AD,
Diocletian established the practice of dividing authority between four co-emperors, in order to better secure the vast territory, putting an end to the
Crisis of the Third Century. During the following decades the empire was often divided along an East/West axis. After the death of
Theodosius I in 395 it was divided for the last time.
The
Western Roman Empire collapsed in 476 as
Romulus Augustus was forced to abdicate by
Odoacer.
The Eastern Roman or
Byzantine Empire ended in 1453 with the death of
Constantine XI and the
capture of Constantinople by the
Ottoman Turks led by
Mehmed II.