300 – 999 AD

300 – Fresco in Catabomb of Saints Marcellinus and Peter in Rome depicts Gospel story of Christ’s healing of the woman with the hemorrhage

300 – 325 – Eusebius Pamphilus, History of the Church

313 – Edict of Milan: Emperors Constantine the Great and Licinius legalize Christianity

325 – Council of Nicaea condemns Arius; defines dogma of the Divinity of Christ

327 – Saint Helena, mother of Constantine, recovers the True Cross

330 – Constantine moves capital to Byzantium

336 – First Celebration of Christmas: Feast of the Nativity of Christ celebrated in Rome, marking the Christianization of the pagan feast of Saturnalia

340 – Saint Athanasius consecrated Bishop of Alexandria; repeatedly deposed by the Arians

355 – 357 The Ordeal of Pope Liberius

Pope Liberius is abducted by the Emperor Constantius, who attempts to force him to sign a statement condemning Athanasius and supporting Arianism. It is unclear whether or not Liberius ever gave in, but even if he did it would not have impacted Papal Infallibility as he would have been coerced. Nevertheless, he is the first Pope not to be named a Saint.

366 – Athanasius restored as Bishop of Alexandria

380 – Christianity becomes official religion of the state

381 – Council of Constantinople defines dogma of the Divinity of the Holy Spirit

382 – Council of Rome defines canon of the Bible under Pope Saint Damasus I; includes seven deuterocanonical books (later rejected by the Protestants)

382 – 406 – Saint Jerome translates the Bible into Latin

387 – Saint Augustine baptized by Saint Ambrose in Milan

400 – Feast of the Commemoration of Mary is celebrated in the East

407 – Saint John Chrysostom dies in exile

410 – Visigoths sack Rome

431 – Council of Ephesus condemns Nestorius; defines dogma of the Divine Maternity of Mary (sanctions title “Mother of God”), affirming the Divinity of Christ

432 – Mission of Saint Patrick to Ireland

451 – Council of Chalcedon defines dogma of the Two Perfect Natures in Christ (divine and human)

452 – Pope Saint Leo the Great dissuades Attila the Hun from sacking Rome

476 – Fall of the Roman Empire

495 – Pope Saint Gelasius I confirms canon of the Bible by decree; includes deuterocanonical books

496 – Baptism of King Clovis I of the Franks

500 – Christ Pantocrator, oldest known icon of Jesus, Monastery of Saint Catherine on Mount Sinai

525 – Saint Benedict establishes Monte Cassino

527 – Dionysius Exiguus estimates years from the Nativity, using designation Anno Domini (A.D.), Latin for “Year of the Lord”

529 – Second Council of Orange denounces Semi-Pelagianism, clarifies role of works and necessity of God’s grace for salvation

536 – 555 – The Case of Pope Vigilius

The Empress Theodora bribes Vigilius and conspires to have him elected Pope in exchange for his support of the Monophysite heresy. Upon being elected Pope, however, Vigilius refuses to go against the orthodox teaching of the Church.

553 – Second Council of Constantinople confirms ruling of Chalcedon

563 – Mission of Saint Columba to Iona

596 – Pope Saint Gregory the Great oversees evangelization of the Anglo-Saxons, England

598 – Gregory the Great forbids mistreatment of the Jews (Letters)

614 – Persian King Chosroes steals the True Cross from Church of the Holy Sepulchre, Jerusalem

622 – Start of Islam, Mohammed claims to receive vision from the Archangel Gabriel

630 – Emperor Heraclius restores the True Cross to Jerusalem

636 – Saint Isidore of Seville dies, last of the Western Fathers

637 – Muslim conquest of Jerusalem

642 – Muslim conquest of Alexandria

680 – 681 – Third Council of Constantinople defines dogma of the Two Perfect Wills in Christ (divine and human)

680 – The Condemnation of Pope Honorius I

The Third Council of Constantinople includes Honorius (d. 638) in a list of heretics. The condemnation, though, is not for the teaching of heresy, but for failing to denounce it. Thus, Papal Infallibility remains intact. In a letter to the Council Pope Saint Agatho, with Honorius in mind, affirms Rome has never fallen into error. The Council agrees with the letter.

700 – Eucharistic Miracle of Lanciano

Bread and wine change visibly into flesh and blood during Mass. Later revealed in scientific tests in 1971 to be human heart tissue and blood, type AB. These elements have remained incorrupt, defying science.

711 – Muslim conquest of Spain

722 – 1492 – Christian reconquest of Spain

726 – Iconoclasm: destruction of sacred images in the East over fear of idolatry

731 – Pope Gregory III condemns Iconoclasm

731 – Saint Bede the Venerable, History of the English Church and People

749 – Saint John of Damascus dies, last of the Eastern Fathers

754 – Martyrdom of Saint Boniface, Apostle of Germany

787 – Second Council of Nicaea declares veneration of sacred images is not idolatry

795 – 1014 – Viking Period: Irish monks save Bible and other books from burning, preserving Western culture

800 – Charlemagne crowned Emperor of the Holy Roman Empire

806 – Martyrs’ Bay: Vikings sack monastery on Iona, killing sixty-eight monks

842 – Synod at Constantinople restores sacred images and declares Feast of Orthodoxy

857 – 878 – Photian Schism

Photius deposes Saint Ignatius, Patriarch of Constantinople. Pope Saint Nicholas the Great rules in favor of Ignatius. Photius condemns the Western Church.

863 – Mission of Saints Cyril and Methodius to the Slavs; invent Cyrillic alphabet

869 – Fourth Council of Constantinople condemns Photius

878 – Pope John VIII acknowledges lawful ascent of Photius after of Ignatius, ending the schism

909 – William the Pius, Duke of Aquitaine, establishes the Congregation of Cluny, center of monastic renewal

929 – Martyrdom of Saint Wenceslaus, Duke of Bohemia

957 – Baptism of Saint Princess Olga of Kiev, Russia

966 – Baptism of Duke Mieszko leads to conversion of Poland

980 – Roswitha of Gandersheim, nun and poetess, earliest known female playwright, composes numerous Christian works

988 – Baptism of Saint Prince Vladimir of Kiev, grandson of Olga, leads to conversion of Russia

993 – First Ritual Canonization; Pope John XV canonizes Saint Ulrich