Approximate birth of Galerius in Dacia.
November 20
Birth of Maximinus Daza to the sister of Galerius.
Galeria Valeria marries Galerius.
The Persians under Narseh defeat Galerius. Diocletian publicly humiliates Galerius by placing the entire blame on him and forces him to walk for a mile ahead of the imperial caravan.
Galerius is reinforced and leads another campaign against northern Mesopatamia. He is joined by his close friend Licinius.
Galerius defeats Narseh in the Battle of Satala and takes his treasury, harem, and wife.
October 1
Galerius takes Nisibis after advancing through Medea and Adiabene.
Arch of Galerius constructed in Thessalonika to commemorate the victory over Narseh.
April
Peace negotiations occur between Narseh and Diocletian with Galerius.
February 24
First of edicts persecuting Christians issues by Diocletian and Galerius.
May 1
Diocletian announces his resignation. Maximian follows suit. Constantius and Galerius are promoted to Augusti, while Severus II and Maximinus are appointed Caesars.
June
Constantius requests his son Constantine I join him in Britain. Galerius grants the request after drinking heavily.
October 28
Maxentius, jealous of the power of Constantine the Great, seizes the title of Emperor. Galerius refuses to recognize him, but is powerless to stop him.
November 11
Galerius calls a council to discuss the disruptive western provinces. Diocletian and Maximian attend. Maximian is forced to abdicate and Constantine the Great is demoted to Caesar under the new Augustus Licinius.
April 30
Galerius posts a letter declaring an end to religious persecutions.
May 1
Death of Galerius from a gruesome disease.