306 Constantine's troops declare him successor to his father, Constantius, in York, and he seizes power in Britain, Gaul and Spain.
306 Constantine married daughter of Maximian, the reluctantly retired Emperor
306 Maxentius, Maximian's son, seizes power in Italy and Africa.
307 Galerius unsuccessfully seeks to restore his appointee, Severus, as Western Caesar.
310 Constantine engineers Maximian's suicide/execution for treason.
311 Great persecution ends with Galerius' Edict of Toleration.
312 Constantine defeats Maxentius at the Battle of Milvian Bridge, Rome and becomes Emperor of the East. He was probably a Christian by this point.
313 At Milan, Licinius marries Constantine's half-sister, Constantia.
313 "Edict of Milan" declares all religions (inc. Christianity) legal.
313 the lenient Caecilian becomes Bishop of Carthage
313 rigorists in Carthage elect Majorinus as their bishop. The majority in Carthage support Majorinus.
313 Donatus succeeds Majorinus and gives his name to the Donatists.
313 Constantine calls Council of Rome, which finds in favour of Caecilian.
314 Constantine calls Council of Arles, which supports both Caecilian and rigorism.
318 Arius condemned for heresy at Alexandria, but has support further east.
324 Constantine defeats Licinius, becoming sole emperor.
324 Constantine denies that he forbids temple sacrifices
324 Constantine writes to Arius and Bishop Alexander of Alexandria.
325 Council of Antioch condemns Arianism and the historian Eusebius of Caesarea.
325 Constantine calls the Council of Nicaea to settle the Arian controversy.
325 Constantine deposes Bishops Eusebius of Nicomedia and Theognis of Nicaea.
327? Constantine readmits Arius, Eusebius and Theognis to the church
328 Athanasius consecrated Bishop of Alexandria
330 renames Byzantium as Constantinople and makes it the imperial capital.
335 Constantine exiles Athanasius to Gaul and restores (pro-Arian) peace in East.
335 dedication of the Church of the Anastasis, Jerusalem
337 Constantine was baptised on his deathbed by Eusebius of Nicomedia and later given a Christian burial in the newly built Church of the Apostles, Nicomedia.