A Prophecy Fulfilled
Several other emperors succeeded Tacitus at short intervals, and all died violent deaths after very brief reigns. Finally the army called Diocletian, an Illyrian soldier, to the throne.
It seems that a northern priestess had once foretold that Diocletian would gain the Roman throne when he had "killed the boar." All the people at this time were more or less superstitious, so Diocletian spent much time hunting. But, although he killed many boars, he was not for a long time named Emperor.
Now the two emperors who came before Diocletian were murdered by a burly soldier named Aper, a Latin word meaning "boar." Some of the legions then elected Diocletian to this office; and he, wishing to punish the murderer for his double crime, struck Aper down with his own hand.
His soldiers were familiar with the prophecy of the priestess, and they now cried that he would surely gain the throne, because he had killed the Boar. True enough, Diocletian's only rival was soon slain, and he was declared emperor by all the Romans.
Diocletian, however, found that the Roman Empire was too large and hard to govern for a single ruler. He therefore made his friend Maximian associate emperor. Then he said that Galerius and Constantius should be called Cæsars, and gave them also a portion of the empire to govern. These four Roman rulers had their capitals at Nicomedia, Milan, Sirmium, and Treves; and now a new epoch begins, with Rome no longer the central point of the government.
Diocletian remained the head and acknowledged leader and adviser of the other rulers. But his reign was troubled by invasions of the barbarians, a war in Persia, and a persecution of the Christians,—the worst and bloodiest that had yet been known.
A lover of solitude and simplicity, Diocletian soon tired of the imperial life. Therefore, when he felt that his strength no longer permitted him to serve the people, he withdrew to a quiet retreat in his native city of Salona, where he spent his last eight years in growing vegetables for his amusement.
As Maximian had retired at the same time as Diocletian, the Roman Empire was now divided between Galerius and Constantius, who were known as emperors of the East and of the West, respectively. Constantius, having obtained the West for his share, went to Britain to suppress a revolt. He died at York, and his son Constantine became emperor in his stead.
Constantine's claim to the empire was disputed by several rivals; but the strongest among them was Maxentius, who ruled Italy and had a large army. On his way to meet him, Constantine became a Christian, thanks to a miracle which the ancient writers relate about as follows.
At noontide, on the day before his battle with Maxentius, Constantine and his army were startled by a brilliant cross, which suddenly appeared in the sky. Around the cross were the Greek words meaning, "By this sign conquer."
Constantine was so moved by this vision that he made a vow to become a Christian if he won the victory. He also ordered a new standard, called a Labarum, which bore the cross, and the inscription he had seen in the skies. This was always carried before him in battle.
Arch of Constantine.
The two armies met near Rome. Maxentius was defeated, and Constantine entered the city in triumph. In memory of his victory a fine arch was built, which is standing still, and is always called the Arch of Constantine.