The Roman Empire is the phase of the ancient Roman civilisation characterise by an autocratic form of government and large territorial holdings in Europe and the Mediterranean. Usually, "Roman Empire" is the term used to describe the Roman state after the establishment of rule by emperors, but is sometimes in non-specialist contexts used more generally to refer to the expansionary Roman state both after and before the time of the first emperor, Augustus. The 500-year-old Roman Republic (509 BC – 1st century BC), which precedes it conceptually, had been weakened by the civil wars of the Late Republic. Losing most of the territory it had acquired at its height between the 4th and 8th century, it continued through major changes until the end of the European Middle Ages, when in 1453 its capital fell to the Ottoman Turks. In its medieval form, it is usually referred to as the Byzantine Empire.