325 CE

Crown Prince Cheng of Jin, age 4, succeeds his father Ming of Jin as emperor of the Eastern Jin dynasty. During his reign, he is largely advised by regents, his uncle Yu Liang and high-level officials. First Council of Nicaea: Constantine summons an ecumenical council of bishops in Nicaea (Turkey). The Nicene Creed, adopted on June 19, declares that the members of the Trinity (the Father, the Son, and the Holy Spirit) are equal. The council decides that Easter is celebrated on the first Sunday after the first full moon after the vernal equinox. Arius is exiled to Illyria; his works are confiscated and consigned to the flames. German and Sarmatian campaigns of Constantine: Emperor Constantine I personally assures the security of the Danube frontier by defeating the Goths, the Vandals and the Sarmatians.

In the 320s, the 4th century.

Geopolitics & Diplomacy

  • German and Sarmatian campaigns of Constantine: Emperor Constantine I personally assures the security of the Danube frontier by defeating the Goths, the Vandals and the Sarmatians.source

Conflict & Security

  • Constantine forbids criminals being forced to fight to the death as gladiators.source
  • Constantine has deposed Emperors Licinius and Martinian executed in Thessalonica and Cappadocia respectively for conspiring and raising troops against him.source

Religion & Belief

  • May 20 – First Council of Nicaea: Constantine summons an ecumenical council of bishops in Nicaea (Turkey). The Nicene Creed, adopted on June 19, declares that the members of the Trinity (the Father, the Son, and the Holy Spirit) are equal. The council decides that Easter is celebrated on the first Sunday after the first full moon after the vernal equinox. Arius is exiled to Illyria; his works are confiscated and consigned to the flames.source

Health & Medicine

  • April 1 – Crown Prince Cheng of Jin, age 4, succeeds his father Ming of Jin as emperor of the Eastern Jin dynasty. During his reign, he is largely advised by regents, his uncle Yu Liang and high-level officials.source

Culture & Society

  • The Colossus of Constantine in the Basilica of Maxentius and Constantine, Rome, is perhaps remodelled at about this date. (The remains are moved to the Palazzo dei Conservatori, Rome, in the 15th century).source

Births

  • Wang Meng (or Jinglüe), Chinese prime minister (died 375)source

Deaths

  • October 18 – Ming of Jin, Chinese emperor (born 299)source
  • Martinian, deposed Roman emperor (executed)source
  • Licinius, deposed Roman emperor (executed)source
  • Tuoba Heru, Chinese prince of the Tuoba Daisource
  • Approximate date – Iamblichus, Syrian philosopher and writer (born 245)source
  • c. July – Li Ju (or Shihui), Chinese general and warlordsource