320s

This is a list of events occurring in the 320s, ordered by year.

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 established his residence in Augusta Treverorum (modern Trier), capital of Germania.
• Licinius reneged 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.
• The Huns appear in Persia. ^{[citation needed]}

By topic

Art

• Old St. Peter's Basilica, Rome, is started to be built (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

• March 7 – Edict of Constantine I: The dies Solis Invicti (Sunday) is proclaimed as the day of rest, trade is forbidden and agriculture is allowed.^[1] Jews continue to observe Sabbath on Saturday, and Constantine himself continues to worship the ancient Roman sun god, Apollo, despite his acceptance of Christianity.
• 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.

Asia

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

By topic

Arts and sciences

• 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 (see 309 AD).

Religion

• The Roman Catholic church is allowed to hold property.
• A synod in Alexandria condemns Arianism.

322

By topic

Technology

• The first dependable representation of a horse rider with paired stirrups was found in China in a Jin Dynasty tomb (China).

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 Jin Mingdi succeeds Jin Yuandi 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 Visgothic force and raids the countryside. This sees Constantine ruling as sole Emperor.
• July – Battle of Hellespont: Crispus, destroys Licinius' naval fleet in the Dardanelles, allowing his father Constantine the ability to cross over the Bosporus into Asian provinces. Byzantium is besieged and Licinius assembled a second military force, under his newly elevated co-emperor Martinian at Lampsacus (modern Lapseki).
• 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 gathered around 30,000 of his surviving troops at Nicomedia.
• 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.

Religion

• St Peter's Church is founded in Rome.
• Eustathius becomes bishop of Antioch.

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 in Thessalonica executed on charge of conspiring, and raising troops against Constantine I.
• Gladiatorial combat is outlawed in the Roman Empire.

China

• April 1 – Crown Prince Jin Chengdi, age 4, succeeds his father Jin Mingdi 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 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 gives order to execute his older son, Crispus Caesar, possibly on charges of adultery.
• Fausta, second wife of Constantine I, is also executed. She is suffocated in a hot bath.
• 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).
• Constantine I promulgates laws against the prostitution of maidservants, and for the humanization of prisons.

By topic

Art

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

Religion

• September 14 – Helena of Constantinople discovers the so-called True Cross and the Holy Sepulchre (Jesus's tomb) in Jerusalem. (traditional date)
• Helena, mother of Constantine I, tells him that he must atone for executing his son and wife by building churches.
• The first church is built on the site of Vatican City, traditional place of Saint Peter's tomb.
• Construction begins on the churches of Golgotha.
• Christianity is introduced to the republic of Georgia by Saint Nino.

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.

By topic

Art

• Old St. Peter's Basilica, Rome, is finished.

Religion

• Christianity is adopted as the state religion of Georgia.
• Construction begins on the cathedral of Antioch (Syria).

328

By place

Roman Empire

• July 5 – The official opening of the Constantine's Bridge built over the Danube between Sucidava (Corabia, Romania) and Oescus (Gigen, Bulgaria) by the Roman architect Theophilus Patricius

By topic

Religion

• May 9 – Alexandria's patriarch Bishop Alexander dies and is succeeded by his deacon Athanasius.

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

• Aurelius Victor, Roman politician and historian

Deaths

References