Galerius (Latin: Gaius Galerius Valerius Maximianus Augustus; c. 260 – April or May 311), was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300. Although he was a staunch opponent of Christianity, Galerius ended the Diocletianic Persecution when he issued an edict of toleration in 311.
Read more about Galerius: Early Life, Persecution of Christians, Rule As Augustus, Death, Anti-Roman Accusations