Byzantine empire By quijadav491 27 BCE 27 BCE Augustus becomes the first roman emperor 313 313 Emperor Constantine I grants freedom of religion, ending persecution of Christians 380 380 Emperor Theodosius I declares Christianity the official religion of the empire. 476 The western Roman empire collapse 527 Justinian Becomes Byzantine emperor 1054 Great schism divides Eastern orthodox and roman catholic churches 1453 Constantinople Falls to the ottoman Turks. Byzantine empire ends