The 320s decade ran from January 1, 320, to December 31, 329.

Events

320

By place

Roman Empire

• Crispus, eldest son of Constantine I, leads a victorious campaign against the Franks, assuring twenty years of peace along the Rhine frontier. He establishes his residence in Augusta Treverorum (modern Trier), capital of Germania.^[1]
• Licinius reneges on the religious freedom promised by the Edict of Milan, and begins a new persecution of Christians in the Eastern Roman Empire. He imprisons Christians, confiscates their properties and destroys churches.

Asia

• King Chandragupta I founds the Gupta dynasty in northern India (approximate date).^[2]
• Zhang Shi (張寔), Zhang Duke of Xiping and governor of Liang Province, (涼州)is assassinated by Yan She (閻涉) and Zhao Ang (趙卬) and replaced by Zhang Mao (張茂), commonly accepted first ruler of the Chinese state Former Liang.

By topic

Art

• Construction begins on the Old St. Peter's Basilica, Rome (approximate date).

Culture and Religion

• In Nydam Mose (Denmark), the Nydam oak boat is sacrificed by the Danes (the boat is excavated in the 1830s, when a local farmer finds weapons, including swords and spears).
• December 25 is introduced as the birthday of Jesus.

Science

• October 18 – Pappus of Alexandria, Greek philosopher, observes an eclipse of the sun and writes a commentary on The Great Astronomer (Almagest).

321

By topic

Roman Empire

• Emperor Constantine I expels the Goths from the Danube frontier and repairs Trajan's Bridge. He leads an expedition into the old province Dacia (modern Romania) and makes peace with the barbarians.
• March 7 - Constantine I signs legislation directing urban residents to refrain from work, and businesses to be closed, on the "venerable day of the Sun". An exception is made for agriculture.

Asia

• Tuoba Heru launches a coup d'état against his cousin Tuoba Yulü and becomes the new Prince of Dai.

By topic

Art and Science

• Calcidius translates Plato into Latin.

Food and Drink

• Constantine I assigns convicts to grind Rome's flour, in a move to hold back the rising price of food in an empire whose population has shrunk as a result of plague.

Religion

• The Christian Church is allowed to hold property.
• A synod held in Alexandria condemns Arianism.
• History of the Jews in Germany: Jews in modern-day Germany are documented for the first time, in Colonia Agrippinensium (modern-day Cologne).^[3]

322

By topic

Technology

• The first dependable representation of a horse rider with paired stirrups is found in China, in a Jin Dynasty tomb.^[4]

323

By place

Roman Empire

• Emperor Constantine the Great defeats the invading Goths and Sarmatians north of the Danube in Dacia, and claims the title of Sarmaticus Maximus.

China

• Crown Prince Ming of Jin succeeds his father Yuan of Jin as emperor of the Eastern Jin Dynasty.

324

By place

Roman Empire

• July 3 – Battle of Adrianople: Emperor Constantine the Great defeats his rival Licinius near Adrianople, forcing him to retreat to Byzantium. He invades Thrace with a Visigothic force and raids the countryside.^[5]
• The Civil wars of the Tetrarchy, which began in 306, end with Constantine ruling as sole Emperor.^[5]
• July – Battle of the Hellespont: Crispus destroys Licinius' naval fleet in the Dardanelles, allowing his father Constantine the ability to cross over the Bosphorus into Asian provinces. Byzantium is besieged and Licinius assembles a second military force, under his newly elevated co-emperor Martinian at Lampsacus (modern-day Lapseki).^[5]
• September 18 – Battle of Chrysopolis: Constantine I definitively defeats Licinius at Chrysopolis, and becomes sole Emperor, thus ending the period of the Tetrarchy. Licinius escapes and gathers around 30,000 of his surviving troops at Nicomedia.^[5]
• December 19 – Licinius abdicates his position as Emperor. He is pardoned by Constantine I as a result of the supplication of his wife Constantia (who is Constantine's halfsister), and banished to Thessalonica as a private citizen.
• Constantine I founds Constantinople and incorporates Byzantium into the new capital. He reorganises the Roman army in smaller units classified into three grades: palatini, (imperial escort armies); comitatenses, (forces based in frontier provinces) and limitanei (auxilia border troops).^[6]

325

By place

Roman Empire

• Emperor Constantine I personally assures the security of the Danube frontier by defeating the Goths, the Vandals, and the Sarmatians.
• Licinius is executed in Thessalonica, on a charge of conspiring and raising troops against Constantine I.^[7]
• Gladiatorial combat is outlawed in the Roman Empire.

China

• 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.

By topic

Art

• Constantine the Great, from the Basilica of Maxentius and Constantine, Rome, is started to be made. It is now kept at Palazzo dei Conservatori, Rome.

Religion

• May 20 – First Council of Nicaea: Constantine I 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.
• The Church of the Nativity is built in Bethlehem.

326

By place

Roman Empire

• Emperor Constantine the Great travels to Rome to celebrate the 20th anniversary of his accession to power, but while en route at Pola he orders his older son, Crispus Caesar, to be executed, possibly on charges of adultery.^[8] Later, Fausta, second wife of Constantine I, is also executed by being suffocated or boiled in a hot bath.^[9]

By topic

Religion

• September 14 (traditional date) – Helena, mother of Constantine I, discovers the so-called True Cross and the Holy Sepulchre (Jesus's tomb) in Jerusalem. On her pilgrimage, she pauses on the Aegean island of Patmos, where she is said to found the church of Panagia Ekatontapiliani.
• Helena tells Constantine that he must atone for executing his son and wife by building churches, and at about this date construction begins on Old St. Peter's Basilica, the first church on the traditional site of Saint Peter's tomb in Rome, and on the basilica of Golgotha on Calvary outside Jerusalem.
• Christianity is introduced to the Kingdom of Iberia (modern-day Georgia) by Saint Nino (approximate date).

327

By place

Roman Empire

• Emperor Constantine the Great decrees that rural slaves can only be sold in the province where they reside, in order to resolve the shortage of labour in the Roman Empire.^[10]

By topic

Religion

• Construction begins on the Great Church of Antioch, which was completed in 341.^[11]
• Approximate traditional date – Helena, mother of Constantine, returning from her pilgrimage to the Holy Land, founds Stavrovouni Monastery on Cyprus.^[12]

328

By place

Roman Empire

• July 5 – Constantine's Bridge, built over the Danube between Sucidava (Corabia, Romania) and Oescus (Gigen, Bulgaria), is officially opened by the Roman architect Theophilus Patricius.^[13]
• December 7 – Lakhmid king Imru' al-Qays ibn 'Amr dies. His epitaph, the Namara inscription, is an important source for the Arabic Language.^[14]

By topic

Religion

• May 9 – Athanasius is elected pope of Alexandria following the death of Alexander I.^[15]

329

By place

China

• The Han-Zhao dynasty, a Southern Xiongnu state during the Sixteen Kingdoms, ends.

By topic

Religion

• Roman restrictions on joining the clergy are initiated.

Significant people

• Constantine I

Births

320

• Aurelius Victor, Roman historian and politician (approximate date)
• Constans I, Roman emperor (d. 350)
• Flavian I, Patriarch of Antioch (d. 404)
• Jin Jianwendi, emperor of the Jin Dynasty (d. 372)
• Oribasius, Greek physician (approximate date)
• Tuoba Shiyijian, prince of the Tuoba Dai (d. 376)
• Xie An, statesman of the Jin Dynasty (d. 385)

321

• Cheng of Jin (or Shigen), Chinese emperor (d. 342)
• Du Lingyang (or Chenggong), Chinese empress (d. 341)
• Valentinian I ("the Great"), Roman emperor (d. 375)^[16]

322

• Kang of Jin (or Shitong), Chinese emperor (d. 344)
• Xun Xian (or Lingze), Chinese general (d. 359)

323

• Constans I, Roman consul and emperor (d. 350)

324

• Chu Suanzi, Chinese empress of the Jin dynasty (d. 384)

325

• Ammianus Marcellinus, Roman historian (approximate date)
• Procopius, Roman general and usurper (approximate date)
• Wang Meng (or Jinglüe), Chinese prime minister (d. 375)

326

• Constantius Gallus, Roman consul and statesman (d. 354)
• Murong Chui (or Daoming), Chinese general (d. 396)

327

• Urban of Langres, French bishop and saint
• Zhang Chonghua, Chinese ruler of Han-Zhao (d. 353)

328

• Flavius Julius Valens, Roman emperor (d. 378)
• Huan Chong, Chinese general and governor (d. 384)
• Yuan Hong, Chinese historian and politician (d. 376)

329

• Gregory Nazianzus, Greek Patriarch of Constantinople (d. 390)

Deaths

320

• January 2 – Narcissus, Argeus, and Marcellinus, Roman Catholic martyrs and saints
• January 29 – Valerius of Trèves, Roman Catholic priest and saint
• February 6 – Dorothea of Alexandria, Roman Catholic virgin, martyr and saint
• March 9 – 40 Martyrs of Sebaste
• March 10 – Cyrion and Candidus, Armenian Orthodox priest and saints
• July 11 – Januarius and Pelagia, Roman Catholic priests, martyrs and saints
• November 29 – Saint Illuminata, Roman Catholic religious sister and saint
• December 9 – Proculus of Verona, Roman Catholic priest and saint

• Lactantius, Christian writer (approximate date)
• Sima Bao, prince of the Jin Dynasty (b. 294)
• Zhang Shi, Duke of Xiping

321

• Tuoba Yulü, Chinese prince of the Tuoba Dai
• Zu Ti (or Shizhi), Chinese general and adviser (b. 266)

322

• Philogonius (or Filogonius), bishop of Antioch
• Rabbah bar Rav Huna, Jewish Talmudist
• Xu Kan, Chinese bandit leader and warlord
• Yang Xianrong, Chinese empress

323

• January 3 – Yuan of Jin (or Jingwen), Chinese emperor (b. 276)
• Tiberius Julius Rhadamsades, Roman prince and client king
• Zhang Bin (or Mengsun), Chinese general and strategist

324

• Guo Pu, Chinese historian, poet and writer (b. 276)
• Wang Dun (or Chuzhong), Chinese warlord (b. 266)
• Zhang Mao, Chinese ruler of Former Liang (b. 277)

325

• October 18 – Ming of Jin, Chinese emperor (b. 299)
• Iamblichus, Syrian philosopher and writer (b. 245)
• Licinius, Roman consul and emperor (executed)
• Li Ju (or Shihui), Chinese general and warlord
• Sextus Martinianus, Roman Emperor (executed)
• Tuoba Heru, Chinese prince of the Tuoba Dai

326

• Flavius Julius Crispus, son of Constantine I (b. 303)
• Flavia Maxima Fausta, Roman empress (b. 289)
• Licinius II, Roman consul and caesar (b. 315)
• Liu (or Xianlie), Chinese empress of Han Zhao

327

• June 3 – Awtel, Eastern Christian monk and saint
• Cleopatra, Christian martyr and saint (or 319)
• Jonas and Barachisius, Persian martyrs
• Melitius of Lycopolis, Christian bishop

328

• Alexander I, pope and patriarch of Alexandria
• Papa (or Papa bar Aggai), Sassanid bishop
• Su Jun, Chinese general and politician
• Yu Wenjun, Chinese empress (b. 297)

329

• Han Huang, Chinese general and rebel
• Liu Xi, Chinese emperor of Han-Zhao
• Liu Yao, Chinese emperor of Han-Zhao
• Liu Yin, Chinese prince of Han-Zhao
• Wen Jiao, Chinese general and governor