Between the reigns of Marcus Aurelius and Diocletian, soldier emperors, whose power came from military experience were usually in control of the Roman Empire.
The Roman Empire was the post-Roman Republic period of the ancient Roman civilization. The Roman Empire was ruled by emperors and had large territorial holdings around the Mediterranean Sea in Europe, North Africa, the Middle East, and the Caucasus. The Empire was a principate ruled from Italy, homeland of the Romans and metropole of the empire, and the city of Rome was its capital.