Maximian, augustus in the West, begins construction…

Galerius is reinforced, probably in the spring of 298, by a new contingent collected from the empire's Danubian holdings.

Narseh does not advance from Armenia and Mesopotamia, leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via the mountains of Armenia.

Diocletian may or may not have been present to assist the campaign.

Narseh retreats to Armenia to fight Galerius' force, to Narseh's disadvantage: the rugged Armenian terrain is favorable to Roman infantry, but unfavorable to Sassanid cavalry.

Local aid gives Galerius the advantage of surprise over the Persian forces, and, in two successive battles somewhere near the Upper Tigris River, Galerius annihilates a much superior Persian force.

During the second encounter, Galerius captures a great deal of plunder, along with King Narseh’s harem and family.

Following up his advantage, he takes the city of Ctesiphon.

Narseh's wife is to live out the remainder of the war in Daphne, a suburb of Antioch, serving to the Persians as a constant reminder of Roman victory.

Galerius advances into Media and Adiabene, winning continuous victories, most prominently near Erzurum, and …

…securing Nisibis (Nusaybin, Turkey) before October 1, 298.

Narseh sues for peace and Galerius compels the Persian monarch to accept Roman terms.

The resultant peace of Nisibis reinstates a Roman protégé in Armenia and gives the empire a part of Upper Mesopotamia that extends to five provinces northeast of the Tigris, which marks the greatest extension of the Roman Empire in the east.

The Persians also recognize the newly installed Roman puppet king of Armenia, Tiridates III; The Romans, for their part, return Narseh’s captive family and concubines.

Peace is thus assured for some decades.

By this treaty, which will last for forty years, the Sassanians withdraw completely from the disputed districts.

Constantius Chlorus’ Campaigns Against the Franks, Saxons, and Alamanni (Late 3rd Century CE)

Constantius Chlorus, a highly capable military commander, took decisive action to secure the western provinces of the Roman Empire, eliminating Frankish and Saxon piracy and defeating the Alamanni in key battles in 298 CE. His victories helped to restore stability to Gaul and reinforce the Rhine frontier, securing his reputation as one of Rome’s greatest generals of the Tetrarchic era.

1. Suppressing Frankish and Saxon Piracy

• The Franks and Saxons, taking advantage of the Crisis of the Third Century, had become notorious for their raids along the coasts of Gaul and Britannia.
• Constantius launched naval and military campaigns to eliminate their bases and prevent further attacks.
• His efforts secured Roman trade routes in the North Sea and the English Channel, stabilizing maritime commerce.

2. Victories Over the Alamanni (298 CE)

• The Alamanni, a powerful Germanic confederation, had been raiding and threatening Roman Gaul.

• In 298 CE, Constantius defeated them in two key battles:

  • Longones (near modern Langres, France) – A strategic victory that expelled Alamannic forces from central Gaul.
  • Vindonissa (modern Windisch, Switzerland) – A major confrontation that further weakened the Alamanni, securing the Rhine frontier.

• These victories reaffirmed Roman dominance in northern and eastern Gaul, reducing the threat of Germanic incursions.

3. Strengthening Rome’s Rhine Defenses

• Following his victories, Constantius focused on fortifying the Rhine frontier, building:

  • New fortresses and military outposts to deter future invasions.
  • Stronger defensive positions along key river crossings and trade routes.

• His military successes secured Gaul for the Roman Empire, preventing major Germanic invasions for decades.

Conclusion: A Master of Defensive Warfare

• Constantius Chlorus' successes against the Franks, Saxons, and Alamanni solidified Rome’s control over the West.
• His ability to eliminate piracy, crush invasions, and reinforce key borders made him a critical figure in stabilizing the empire after the Crisis of the Third Century.
• His military reputation ensured that after Diocletian’s abdication in 305 CE, he was recognized as Augustus of the West, setting the stage for the rise of his son, Constantine the Great.

Constantius Chlorus’ campaigns in Gaul and along the Rhine frontier played a key role in restoring Roman strength, allowing the empire to survive and adapt in the centuries to come.

Domitianus' corrector, Aurelius Achilleus, who is responsible for the defense of Alexandria, is the possible successor to Domitianus' claim for the purple.

Achilleus is at length taken by Diocletian after a siege of eight months in Alexandria, and put to death.

Diocletian's accession in 284 had not marked an immediate reversal of disregard to Christianity, but it had heralded a gradual shift in official attitudes toward religious minorities.

In the first fifteen years of his rule, Diocletian has purged the army of Christians, condemned Manicheans to death, and surrounded himself with public opponents of Christianity.

Diocletian's preference for activist government, combined with his self-image as a restorer of past Roman glory, presage the most pervasive persecution in Roman history.

Constantius has also fought the Berber tribes in Africa in 296-298, triumphing at Carthage.

Maximian, who campaigns also in northern Africa against the local tribes in 297-299, attacks the Moors in Spain as well.

Empress Jia and and her clan remain in power until 300, when she deposes and assassinates the heir to the throne, Sima Yu, her husband's son by the concubine Consort Xie Jiu.

Sima Lun, who commands the imperial guards, takes this opportunity to kill the Empress Jia and her faction.

Sima Lun places himself in power and tries to centralize control over the powerful princes; this results in the rebellion of Sima Yun, who marches his troops to the capital against Sima Lun; Sima Yun is killed by Sima Lun's troops in the ensuing battle in Luoyang.

Sima Lun then imprisons Emperor Hui and styles himself as the new emperor.

The books now known as the Corpus Hermeticum are part of a renaissance of syncretistic and intellectualized pagan thought that took place around the second century.

Other examples of this cultural moment include Neoplatonist philosophy, the Chaldaean Oracles, late Orphic and Pythagorean literature, as well as much of Gnosticism.

The corpus of Hermetica, the category of popular Late Antique literature purporting to contain secret wisdom, and generally attributed to Hermes Trismegistus, "thrice-great Hermes", a syncretism of the Greek god Hermes and the Egyptian Thoth, is by 300 essentially complete.

The hieroglyphic-based cursive script of Egyptian Demotic gives way around the same time to Coptic, written in an alphabet based on Greek and comprising many dialects.

The realistic style now dominant in Roman portraiture echoes both the style and the technique of Egyptian mummy portraits.

The floor of a Roman villa in southeastern Sicily near the present town of Piazza Armerina boasts a spectacular series of multicolored mosaics thought to have been set around 300 by artisans from North Africa.

Covering an area of about forty-two hundred square yards (thirty-five hundred square meters), the pavements feature large figures distributed seemingly at random in crowded, spaceless fields.

One major scene depicts the hunting and capture of African animals for shipment to Rome; others represent women exercising, the circus, seascapes, cupids at play, and mythological themes.