310-329 Eastern Emperors Gain Power Over Rome

This 20 year period  started with the Carnuntum Conference convened by the Eastern Roman Emperor Galerius pictured to restore order among those contending to be the western emperor. This conference was attended by Diocletian.

Maximian -- the Western emperor -- was forced to abdicate, and his son, Maxentius, was denied any status. A new emperor for the west was appointed - Licinius, a general - and Constantine remained as his co-ruler.

Maximian still yearned for power and was forced to commit suicide after an attempt to overthrow his son-in-law Constantine in 310.

To complicate matters, Galerius' co-ruler, Maximinus, resented the elevation of Licinius and to keep peace, Galerius made him his co-emperor.

In 311 Galerius died and Maximinus, implacably against the Christians, took over.

To secure his position, Constantine offered the marriage of his sister, Constantia, to Licinius, Emperor of the West.

Maximinus, Emperor of the East, promised Maxentius, living in Rome, the emperorship of the west, causing Constantine to invade Italy in 312. At the Battle of the Mulvian Bridge outside Rome Maxentius met Constantine (who used a Christian symbol on his shield) and Maxentius was defeated.

In the following year 313, while Licinius was in Rome marrying Constantine's sister, Maximinus marched across Asia Minor, taking Byzantium and crossed into Europe.

The armies of the east and west met, Maximinus fled, abandoning his army, and Licinius pursued him to Tarsus in Asia Minor, besieged him and finally he committed suicide.

Licinius kept his promise to Constantine about restoring church property taken by Maximinus, and was ruthless in eradicating all members - including women and children - of the families involved in persecuting Christians (far more ruthless than the previous emperors had been against members of the sect).

Amazingly, after Licinius had got rid of all of Constantine's rivals, and done much of his dirty work for him, Constantine then feared Licinius in his position as new Emperor of the East - with a male heir, Constantine's own nephew - and declared war on him in 316, got as far as Byzantium but was outsmarted by Licinius and retreated.

Previously sympathetic to Christians, Licinius now saw them as treacherous and protected himself by dismissing them from his service.

By 321 the empire was split, and wanting total control Constantine amassed a huge force and invaded Licinius's territory northwest of Thessalonica, northern Greece, and in 324 the two armies did battle. Licinius fell back and was finally defeated near Chalcedon. Licinius's life was spared when his wife (Constantine's sister) and the Bishop of Nicomedia interceded.

With Licinius's abdication, Constantine became the first emperor in 40 years to rule the empire on his own and immediately became embroiled in complicated Christian theological disputes, necessitating calling a Church Council in 325, held in Nicaea, attended by 300 bishops mainly from the east, though largely a Greek affair - its decisions were to be binding in the west as well and became known as the Nicene Creed.

As well as setting a fixed date for Easter, this council also eradicated Jewish customs from the service.

290-309 Diocletian Splits Empire into West & East

In this 20 year period  the Roman Emperor Diocletian (pictured) appointed Maximian as co-emperor, but the threats from all parts of the empire were such that in 293 he appointed the Germans Constantius (married to Maximian's daughter) to rule the west and Galerius (married to Diocletian's daughter) to rule the east - though the boundaries were fluid, each man helping the other.

In 293 the Persian throne had been seized by a new king who drove the Romans out of Armenia - Galerius in 298 defeated the Persians and wanted to advance further, but Diocletian checked him, negotiating a stronger Roman position with the Persians, giving the Romans full control of Armenia and northern Mesopotamia.

By late 290s, peace restored to the Empire, enabling Diocletian to pay attention to administrative affairs - particularly the murder of emperors by soldiers. He proclaimed that emperors were ordained by the gods to rules, and introduced an elaborate ceremonial intended to mark the emperor as being superior to normal human beings, requiring prostration before the emperor by commoners and kneeling and kissing the hem of the robe by higher ranks. He also created rules for imperial appearances whereby emperors were not allowed to act like normal human beings.

He also reformed the structure of provincial government, by increasing the number of provinces by dividing them into smaller units, and then each province into twelve dioceses. He also stripped the governors of command over the armies. He also initiated a capitation system of taxation, requiring regular censuses (which later lea to extensive legislation prohibiting peasants from leaving the land under which they had been entered into the census).

Then he attempted a policy of social uniformity by imposing upon everyone the observance of Roman traditions. Hence the Great Persecution of the Christians.

He outlawed marriage with close female relatives (a Roman custom that had not been applied to non-Romans); and banned the Manichaean religion (founded in 240 by Mani, a resident of Persian controlled Mesopotamia, inspired by Gnosticism and Zoroastrianism, by which believers gained salvation through him - very similar to Christianity).

Starting with his own household, he threatened to dismiss anyone who refused to act like a Roman, and in 303 prohibited Christian religious assemblies, demolished churches and burnt liturgical books, arresting church leaders who refused to act like a Roman. These measures were pursued with determination in the east, especially Africa, but less so in the west where few Christians.

In 303 Diocletian abdicated - persuading Maximian to do likewise - giving power to Constantius in the west and Galerius in the east who appointed their own co-rulers.

Galerius appointed his nephew Maximinus as co-ruler, and urged Constantius to appoint Severus, a general, as his co-ruler in the west, but within a year, in 306, Constantius died, precipitating his son, Constantine, to pronounce himself Emperor of the West, but acting as senior emperor Galerius coerced him to be Severus' co-ruler and so Severus became Emperor of the West.

Constantine acquiesced for the moment and distinguished himself by establishing his authority over Britain, Gaul and Spain and in his new capacity as co-ruler rescinded his father's edicts against the Christians and became their savior.

Meanwhile Maximian's son, Maxentius, followed Constantine's lead and took advantage of dissent in Rome to have himself declared as Emperor in 306.

Galerius refused him recognition and ordered Severus to remove him by force, but faced with Maximian suddenly re-claiming the emperorship from his son, Maxentius, Severus was forced to abdicate and was eventually killed.

Galerius finally invaded Italy in 307, wanting the re-instatement of Severus, but was defeated and had to withdraw.

Then Maxentius argued with his father about who was the rightful emperor.

In the meantime, Constantine remained neutral as the co-ruler of the west - despite the fact that he had married Maxentius' sister and was therefore involved in the family struggle whether he liked it or not.

When the army sided with Maxentius, Maximian fled to Constantine's court in the west.