Re: Event of the Year
 

321

Battle of Wogastisburg between the Slavs led by Samo, and the Franks led by their king, Dagobert I.

Re: Event of the Year
 

320

Under Crispus, son of Constantine I, the Franks are defeated again, assuring twenty years of peace along the Rhine border.

Re: Event of the Year
 

319

Constantine prohibits the separation of the families of slaves during a change in ownership.

Re: Event of the Year
 

318

Gregory the Illuminator appoints his son Aristax as successor in the Patriarchate of Armenia.

Re: Event of the Year
 

317

King Mirian II of Caucasian Iberia declares Christianity the official state religion.

Re: Event of the Year
 

316

* Edict of Constantine I issued in favour of slaves: he prohibits punishing them by crucifixion and facial branding.
* December - Constantine I defeats Licinius in the Battle of Mardia, and gains some of his colleague's territory

Re: Event of the Year
 

315

Constantine and Licinius battle the Sarmates, the Goths and the Carpians along the Danube. They reestablish the defence of the frontier.

Re: Event of the Year
 

314

8 October - War between Constantine I and Licinius. Licinius is defeated at the Battle of Cibalae and loses all of his territory in Europe.

Re: Event of the Year
 

313

Arius preaches of the human nature of Jesus.

Re: Event of the Year
 

312

Battle of Milvian Bridge: Constantine I defeats Maxentius and becomes the only Roman Emperor in the West. During the battle, he reportedly has a vision of a cross with the words in hoc signo vinces ("In this sign you shall conquer").