Roman Timeline of the 4th Century AD

Year	Event
301 AD	Diocletion's maximum price edicts go into effect.
303 AD	Diocletion persecutes the Christians in earnest.
305 AD	Diocletian and Maximian abdicate the throne. Galerius and Constantius Chlorus co-Augusti
306 AD	Death of the Emperor Constantius Chlorus in the city of Ebaracum. Constantine named Augustus in the West.
306 AD	Emperor Fl. Valerius Severus revolts and invades Italy. His father Maximian comes out of retirement first in his support, then in favor of Constantine. Severus killed in Pannonia and Maximian recognized as co-emperor.
308 AD	Marcellus is appointed as the new Pope in Rome. Exiled in 309 and replaced by Eusebius.
308 AD	The Conference of Carnutum, a meeting of all of the Caesars and Augusti, eventually setting off civil war.
310 AD	Death of Maximian after the siege of Masillia by Constantine.
311 AD	Publication of the Edict of Toleration by the Emperor Galerius, ending Christian persecution, followed shortly by his death. Death of Diocletion.
312 AD	Constantine leads his army from Gaul, investing several towns and winning the support of most of Italy. On the march to Rome, he claimed to have seen the sign of a cross of light, and the words "By this sign, conquer". This is the basis for speculation on Constantine's Christian conversion
312 AD	Death of the emperor Maxentius after Constantine's victory at the battle of the Milvian Bridge. Constantine disbands the Praetorian guard.
313 AD	Victory of Licinius over Maximinus Daia at the Hellespont is followed by reconciliation of Constantine and Maximinius. Edict of Milan is signed by Emperor Constantine the Great and the Emperor Licinius setting a tone for peace and Christian acceptance.
314 AD	Peace is interrupted once again when armed conflict breaks out between the co-emperors. Periods of war and peace follow for ten years with Constantine increasingly victorious.
315 AD	The arch of Constantine is erected in Rome.
316 AD	Battle of Campus Ardiensis in which Constantine defeats Licinius.
317 AD	Birth of Constantine II, in the city of Arelate.
320 AD	Birth of the Emperor Constans, in the city of Constantinople.
322 AD	St. Peter's Church is constructed in Rome.
323 AD	Constantine drives the Goths out of Thracia.
324 AD	Final victory for Constantine over Licinius at Adrianople and Chrysopolis. Constantine sole emperor.
325 AD	The Council of Nicaea makes Christianity the religion of the Empire
326 AD	Constantine executes his son, Crispus, followed by his wife Faustus a year later. She was boiled alive.
326 AD	Constantine chooses Byzantium as the new capital of the Empire and renames it Constantinople.
328 AD	Birth of the Emperor Valens, in the city of Cibalae.
332 AD	Birth of the Emperor Julian the Apostate.
336 AD	The Church of the Holy Sepulchre is built and dedicated in Jerusalem.
337 AD	Constantine had himself baptized by Eusebius, the bishop of Nicomedia. Shortly before his death. Division of the empire between Constantine's three sons: Constantine II (west), Constans (middle), Constantius (east).
339 AD	Birth of the bishop of Milan, Ambrose, in the city of Trier.
340 AD	Civil war once again. Death of Constantine II against Constans at the battle of Aquileia.
341 AD	Emperor Constans begins a successful campaign against the Franks.
343 AD	The Emperor Constans campaigns against the Picts and Scots in Britannia, whom he successfully drives back into Caledonia.
344 AD	Persian victory at Singara.
347 AD	Birth of the Emperor Theodosius the Great, in the town of Cauca, Northwestern Spain.
348 AD	Birth of Saint Jerome, the Christian writer.
350 AD	Death of the Emperor Constans after a revolt broke out under Magnentius. The Persians invade and take Armenia.
351 AD	Emperor Constantius II defeats the army of the pretender Magnentius in a battle near Mursa.
353 AD	Battle of Mons Seleucus in which Contantius defeats Magnentius in a bloody engagement.
357 AD	Julian defeats the Alemmani.
359 AD	Sapor II invades Mesopotamia. Constantius goes to the east. Birth of the Emperor Gratian, in the town of Sirmium.
360 AD	Julian's army proclaims him emperor and he marches east.
361 AD	Death of Constantius II, Julian the Apostate takes over.
362 AD	Julian outlaws the teaching of Christianity.
363 AD	Battle of Ctesiphon, in which Julian defeats Shapur II, but Julian is killed in the battle. Jovian emperor.
364 AD	Jovian reverses Julians anti-Christian edicts. Nominates Valentinian as his heir and dies. Valentinian makes his brother Valens eastern emperor and takes the west for himself. Permanent separation of the empire.
367 AD	Valentinian defeats the Alemmani at Solicinium.
368 AD	Valens at war with the Goths.
369 AD	Peace with Goths
369 AD	Huns invade Ostrogoth territory.
370 AD	Theodosius drives invading Picts out of Britain once again.
371 AD	Birth of the Emperor Valentinian II.
374 AD	Theodosius the Great campaigns against the Sarmatians along the Danube.
374 AD	Ambrose appointed bishop of Milan.
375 AD	Death of Valentinian. Followed by Gratian who also promoted his infant brother Valentinian II at Milan. Gratian is the first emperor to refuse the office of Pontifex Maximus.
376 AD	Theodosius the Elder is killed in Africa and his son, the Great retires from public service.
377 AD	Emperor Valens and Emperor Gratian combine against Visigoth and Ostrogoth armies along the Danube. Goths move into Thracia. Birth of the Emperor Arcadius, in Spain.
378 AD	Gratian defeats Alemanni. The Romans, under Valens are then defeated badly at Adrianople by Fritigern and the Goths. Perhaps the most terrible and unrecoverable defeat in Roman history. Valens killed.
379 AD	Gratian nominated Theodosius (the Great) to replace Valens.
380 AD	Theodosius the Great declares Christianity to be the sole religion of the empire.
382 AD	Treaty of Theodosius with Visigoths.
383 AD	Revolt of Maximus in Britain. Death of Gratian. Theodosius recognizes Maximus in the west and Valentinian II at Milan. Birth of the Emperor Honorius.
387 AD	Emperor Theodosius signs a treaty with the Persian King Shapur III, giving Persia four fifths of Armenia, and Rome one fifth. He then crushed Maximus at Aquileia.
390 AD	Birth of the Roman general Flavius Aetius.
391 AD	Paganism is officially ended with edicts published by Emperor Theodosius.
392 AD	Death of the Emperor Valentinian II. Eugenius replaces him, set up by the Germanic general Arbogast.
394 AD	The last showing of the ancient Olympic Games is held in this year after it is banned by Emperor Theodosius the Great. There are no games again until 1896.
394 AD	Theodosius and the Germanic Alaric defeat Arbogast at the River Frigidus.
395 AD	Death of Theodosius the Great. His sons Honorius takes the west, and Arcadius the east. The Huns invade Armenia, Cappadocia and Syria.
395 - 397 AD	Alaric invades the Balkans but is checked by Stilicho. Alaric set up as governor of Illyricum.
399 AD	Ostrogoths invade and capture Galatia, Pisidia, and Bithynia.

Roman Timeline of Events - Table of Contents

Did you know...
Constantine's victory at the Milvian Bridge counts among the most decisive moments in world history, while his legalization and support of Christianity and his foundation of a 'New Rome' at Byzantium rank among the most momentous decisions ever made by a European ruler.