The Tetrarchy was the system instituted by Roman emperor Diocletian in 293 AD to govern the ancient Roman Empire by dividing it between two emperors, the augusti, and their junior colleagues and designated successors, the caesares.
The 310s decade ran from January 1, 310, to December 31, 319.
The 320s decade ran from January 1, 320, to December 31, 329.
Year 321 (CCCXXI) was a common year starting on Sunday of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Crispus and Constantinus. The denomination 321 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 325 (CCCXXV) was a common year starting on Friday of the Julian calendar. At the time, it was known as the Year of the Consulship of Proculus and Paulinus. The denomination 325 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 324 (CCCXXIV) was a leap year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Crispus and Constantinus. The denomination 324 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 313 (CCCXIII) was a common year starting on Thursday of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantinus and Licinianus. The denomination 313 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. This year is notable for ending of the persecution of Christians in the Roman Empire.
Year 306 (CCCVI) was a common year starting on Tuesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Valerius. The denomination 306 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 307 (CCCVII) was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Maximinus. The denomination 307 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 310 (CCCX) was a common year starting on Sunday of the Julian calendar. At the time, it was known as the Year of the Consulship of Andronicus and Probus. The denomination 310 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 311 (CCCXI) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerius and Maximinus. The denomination 311 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Year 320 (CCCXX) was a leap year starting on Friday of the Julian calendar.
Year 316 (CCCXVI) was a leap year starting on Sunday of the Julian calendar. At the time, it was known as the Year of the Consulship of Sabinus and Rufinus. The denomination 316 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Valerius Licinianus Licinius was Roman emperor from 308 to 324. For most of his reign, he was the colleague and rival of Constantine I, with whom he co-authored the Edict of Milan that granted official toleration to Christians in the Roman Empire. He was finally defeated at the Battle of Chrysopolis, and was later executed on the orders of Constantine I.
Galerius Valerius Maximinus, born as Daza, was Roman emperor from 310 to 313. He became embroiled in the civil wars of the Tetrarchy between rival claimants for control of the empire, in which he was defeated by Licinius. A committed pagan, he engaged in one of the last persecutions of Christians, before issuing an edict of tolerance near his death.
The Battle of Cibalae was fought in 316 between the two Roman emperors Constantine I and Licinius. The site of the battle, near the town of Cibalae in the Roman province of Pannonia Secunda, was approximately 350 kilometers within the territory of Licinius. Constantine won a resounding victory, despite being outnumbered.
The Battle of Mardia, also known as Battle of Campus Mardiensis or Battle of Campus Ardiensis, was fought in late 316/early 317 between the forces of Roman Emperors Constantine I and Licinius. Its location was probably modern Harmanli (Bulgaria) in Thrace.
Martinian was Roman emperor from July to September 324. He was raised to the purple by the emperor Licinius, whom he had hitherto served as a senior bureaucrat, during Licinius's civil war against the emperor Constantine I. Constantine defeated both emperors and forced them to abdicate, and executed them after initially showing leniency.
Aurelius Valerius Valens, rarely enumerated as Valens I, was briefly Roman emperor from late 316 to early 317. He was proclaimed emperor by Licinius, emperor of the East, during his war against Constantine I, emperor of the West.
Licinius II, also called Licinius Junior or Licinius Caesar, was the son of the Roman emperor Licinius I. He held the imperial rank of caesar between March 317 and September 324, while his father was augustus, and he was twice Roman consul. After losing a civil war, his father lost power and both he and Licinius Junior were eventually put to death.
