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451 Council of Chalcedon (Fourth Ecumenical), convened by Emperor Marcian and his wife Empress Pulcheria, presided over by Eusebius of Dorylaeum, and attended by 630 bishops all together. It condemns Eutychianism as well as the Monophysitism of Dioscorus (the belief that the two natures of Christ had become one nature after the Incarnation), exonerates those who had been unlawfully deposed by the Robber Council, rejects the acts of that council, except those found to be Orthodox and canonical.

452 Proterios of Alexandria convenes synod in Alexandria to reconcile Chalcedonians and non-Chalcedonians; second finding of the Head of John the Forerunner.

457 Victorius of Aquitania computes new Paschalion; first coronation of Byzantine Emperor by patriarch of Constantinople.

459 Death of Symeon the Stylite.

461 Death of Leo the Great and Patrick of Ireland.

462 Indiction moved to September 1; Studion Monastery founded.

466 Church of Antioch elevates bishop of Mtskheta to rank of Catholicos of Kartli, rendering the Church of Georgia autocephalous; death of Shenouda the Great, abbott of White Monastery in Egypt, considered the founder of Coptic Christianity.

471 Patr. Acacius of Constantinople first called Oikoumenikos ("Ecumenical").

473 Death of Euthymius the Great.

475 Emperor Basiliscus issues letter to bishops of empire, supporting Monophysitism.

477 Timothy Aelurus of Alexandria exiles Chalcedonian bishops from Egypt.

482 Byzantine emperor Zeno I issues Henoticon.

484 Acacian Schism.

484 Founding of Mar Sabbas Monastery by Sabbas the Sanctified; Synod of Beth Lapat in Persia declares Nestorianism as official theology of Assyrian Church of the East, effectively separating the Assyrian church from the Byzantine church.

489 Emperor Zeno I closes Nestorian academy in Edessa, which was then transferred under Sassanian Persian auspices to Nisibis, becoming the spiritual center of the Assyrian Church of the East.

490 Brigid of Kildaire founds monastery of Kildare in Ireland.

494 Pope Gelasius I of Rome delineates relationship between Church and state in his letter Duo sunt, written to Emperor Anastasius I.

496 Remigius of Rheims baptizes Franks into Orthodox Christianity.

500 Pseudo-Dionysius the Areopagite writes The Mystical Theology.

506 Church of Armenia separates from Chalcedonian Orthodoxy.

507 Clovis I defeats the Arian Visigoths at Battle of Vouillé near Poitiers, ending their power in Gaul.

518 Severus of Antioch deposed by Emperor Justin I for Monophysitism; Patr. John II of Constantinople is addressed as Oikoumenikos Patriarches ("Ecumenical Patriarch").

519 Eastern and Western churches reconciled with end of Acacian Schism.

521 Birth of Columba of Iona.

527 Dionysius Exiguus calculates the date of birth of Jesus incorrectly; foundation of St. Catherine's Monastery on the Sinai peninsula by Justinian the Great.

529 Pagan University of Athens closed and replaced by Christian university in Constantinople; Benedict of Nursia founds monastery of Monte Cassino and codifies Western monasticism; Council of Orange condemns Pelagianism; death of Theodosius the Great.

529-534 Justinian's Corpus Juris Civilis issued.

530 Brendan the Navigator lands in Newfoundland, Canada, establishing a short-lived community of Irish monks.

532 Justinian the Great orders building of Hagia Sophia; death of Sabbas the Sanctified.

533 Mercurius elected Pope of Rome and takes the name of John II, first pope to change name upon election.

534 Roman Empire destroys the Arian kingdom of Vandals.

536 Menas of Constantinople summons a synod anathematizing Severus of Antioch.

537 Construction of Hagia Sophia in Constantinople completed.

538 Emperor Justinian the Great, via deportations and force, manages to get all five patriarchates offcially into communion.

539 Ravenna becomes exarchate of Byzantine Empire.

541 Jacob Baradeus organizes the Non-Chalcedonian Church in western Syria (the "Jacobites"), which spreads to Armenia and Egypt.

543 Doctrine of apokatastasis condemned by Synod of Constantinople.

544 Jacob Baradeus consecrates Sergius of Tella as bishop of Antioch, opening the lasting schism between the Syriac Orthodox Church and the Chalcedonian Church of Antioch; founding of the monastery at Clonmacnoise in Ireland by Ciaran.

545 David of Wales moves primatial see of Britain from Caerleon to Menevia (St. Davids's).

546 Columba founds monastery of Derry in Ireland.

547 David of Wales does obeisance to the Patriarch of Jerusalem.

553 Council of Constantinople (Fifth Ecumenical), convened by Roman Emperor Justinian I, presided over by Menas of Constantinople, and attended by 165 bishops. It is convened firstly in order to condemn Origenism (belief in the preexistence of souls, reincarnation, that hell is only temporary, that demons will be saved, that there will not be a bodily resurrection, that various inanimate objects contain souls), and secondly in order to condemn the writings of Theodore of Mopsuestia, Theodoret of Cyrus and Ibas of Edessa, on the charge of Nestorianism. These latter condemnations are hurled mainly to please the Monophysites, making union more possible. Thereby it appears that the council is siding with the Monophysites. Pope Vigilius of Rome disagrees at first but is later convinced to sign the edict. This, however, causes schisms in the West.

553 Bishops of Aquileia, Milan, Venetia and the Istrian peninsula in Italy all refuse to condemn the Three Chapters, causing Schism of the Three Chapters in those areas, leading to independence of Patriarch of Venice from Patriarch of Aquileia; Ostrogoth kingdom conquered by the Byzantines after the Battle of Mons Lactarius.

554 Church of Armenia officially breaks with West in 554, during the second Council of Dvin where the dyophysite formula of Chalcedon was rejected.

556 Columba founds monastery of Durrow in Ireland; death of Roman the Melodist.

557 Brendan the Navigator founds monastery at Clonfert, Ireland.

563 Columba arrives on Iona and establishes monastery there, founding mission to the Picts.

569 Final schism between Chalcedonians and non-Chalcedonians in Egypt; David of Wales holds Synod of Victoria to re-assert anti-Pelagian decrees of Brefi.

576 Dual hierarchy henceforth in Alexandria, Chalcedonian (Greek) and Monophysite (Coptic).

577 Patr. John III Scholasticus is responible for the first collection of Canon Law, the Nomocanon, of the Orthodox Church.

579 400 Martyrs slain by Lombards in Sicily.

580 Monte Cassino sacked by Lombards, sending its monks fleeing to Rome; Slavs begin to migrate into the Balkans and Greece.

587 Visigoth King Reccared renounces Arianism in favor of Orthodoxy.

589 Council of Toledo adds Filioque to Nicene-Constantinopolitan Creed in an attempt to combat Arianism.

590 Columbanus founds monasteries in France.

593 Anastasius the Sinaite restored as Orthodox Patriarch of Antioch.

596 Gregory the Dialogist sends Augustine along with forty other monks to southern Britain to convert pagans.

597 Death of Columba of Iona.

598 Glastonbury Abbey founded.

600 The Ladder of Divine Ascent written by John Climacus; Gregory the Dialogist inspires development of Gregorian Chant through his liturgical reforms.

601 Augustine of Canterbury converts King Ethelbert of Kent and establishes see of Canterbury.

602 Augustine of Canterbury meets with Welsh bishops to bring them under Canterbury.

604 Mellitus becomes first bishop of London and founds first St. Paul's Cathedral; death of Gregory the Dialogist.

605 Death of Augustine of Canterbury.

610 Heraclius changes official language of the Empire from Latin to Greek, already the lingua franca of the vast majority of the population.

612 Holy Sponge and Holy Lance brought to Constantinople from Palestine.

614 Persians sack Jerusalem under Chosroes II of Persia; Church of the Holy Sepulchre damaged by fire, True Cross captured, and over 65,000 Christians in Jerusalem massacred.

615 Death of Columbanus in Italy.

617 Persian Army conquers Chalcedon after a long siege.

626 Akathist Hymn to the Virgin Mary written.

627 Emperor Heraclius defeats Sassanid Persians at Battle of Nineveh, recovering True Cross and breaking Sassanid power.

630 Second Elevation of the Holy Cross.

633 Death of Modestus of Jerusalem.

635 Founding of Lindisfarne Monastery by Aidan; Cynegils, king of Wessex, converts to Christianity.

636 Capture of Jerusalem by Muslim Arabs after Battle of Yarmuk.

640 Muslim conquest of Syria; Battle of Heliopolis between Arab Muslim armies and Byzantium opens door for Muslim conquest of Byzantine Exarchate of Africa.

641 Capture of Alexandria by Muslim Arabs.

642 Muslim conquest of Egypt.

646 Alexandria recaptured by Muslim Arabs after Byzantine attempt to retake Egypt fails, ending nearly ten centuries of Greco-Roman civilization in Egypt.

648 Pope Theodore I of Rome excommunicates patriarch Paul II of Constantinople.

649 Arabs invade and conquer Cyprus.

650 Final defeat of Arianism as Lombards convert to Orthodoxy.

653 Pope Martin the Confessor arrested on orders of Byzantine Emperor Constans II.

654 Invasion of Rhodes by Arabs.

655 Martyrdom of Martin the Confessor.

657 Founding of Whitby Abbey in Yorkshire, England.

662 Death of Maximus the Confessor.

663 Emperor Constans II is last Eastern emperor to set foot in Rome; Constans II declares Pope of Rome to have no jurisdiction over Archbishop of Ravenna, since that city was the seat of the exarch, his immediate representative.

664 Synod of Whitby held in northern England, adopting Roman calendar and tonsures in Northumbria; Ionian monk Wilfrid appointed as Archbishop of York.

669-78 First Arab siege of Constantinople; at Battle of Syllaeum Arab fleet destroyed by Byzantines through use of Greek Fire, ending immediate Arab threat to eastern Europe.

670 Composition of Caedmon's Hymn by Caedmon of Whitby.

672 First Synod of Hertford called by Theodore of Tarsus, adopting of ten decrees paralleling the canons of the Council of Chalcedon.

673 Second Council of Hatfield upholds Orthodoxy against Monothelitism.

680-681 Council of Constantinople  (Sixth Ecumenical), convened by Emperor Constantine Pogonatus, presided over by St. George of Constantinople, and attended by 170 fathers. It condemns Monothelitism and anathematizes the Monothelite Patriarchs Cyrus of Alexandria, Sergius, Pyrrhus, Paul and Peter of Constantinople, Pope Honorius of Rome, and Bishop Theodore of Pharan. They are then replaced with Orthodox successors.

682 Foundation of Monkwearmouth-Jarrow Abbey in England.

685 First monastics come to Mount Athos; death of Anastasius of Sinai.

685 John Maron elected first Maronite patriarch, founding the Maronite Catholic Church, which embraced Monothelitism, rejected the teaching of the Fifth Ecumenical Council, and separated from the Orthodox Church.

687 Destruction of Whitby Abbey by Danish Vikings; death of Cuthbert of Lindisfarne.

688 Emperor Justinian II and Caliph al-Malik sign treaty neutralizing Cyprus.

690 Witenagamot of England forbids church appeals to Rome.

691 Dome of the Rock completed in Jerusalem.

692 Council of Trullo in Constantinople (Quinisextine - Fifth-and-Sixth Council), convened by Roman Emperor Justinian II Rhinotmetus, presided over by Paul of Constantinople, and attended by 327 bishops, establishes canons regarding church order and discipline, canons which the Fifth and Sixth Ecumenical Councils had been unable to establish.

694 Byzantine army of Justinian II defeated by Maronites, who became fully independent.

697 Council of Birr accepts Roman Paschalion for northern Ireland; at this synod, Adomnán of Iona promulgates his Cáin Adomnáin.

698 Muslim conquest of Carthage; at Synod of Aquileia, bishops of the diocese of Aquileia end the Schism of the Three Chapters and return to communion with Rome.

700 Death of Isaac of Syria.

707 Death of John Maron.

710 Pope Constantine makes last papal visit to Constantinople before 1967.

712 Death of Andrew of Crete.

715 Lindisfarne Gospels produced in Northumbria (Northern England).

715 Grand Mosque of Damascus built over the Cathedral of St. John the Baptist; Al-Aqsa Mosque constructed over site of Church of St. Mary of Justinian; Pictish King Nechtan invites Northumbrian clergy to establish Christianity amongst the Picts.

716 Monastery at Iona conforms to Roman liturgical usage; Boniface's first missionary journey to Frisia.

717 Pictish king Nechtan expels monks from Iona.

717-18 Second Arab siege of Constantinople.

719 Nubian Christians transfer allegiance from Chalcedonian church to Coptic church.

723 Boniface fells Thor's Oak near Fritzlar.

726 Iconoclast Emperor Leo the Isaurian starts campaign against icons.

730 Leo the Isaurian orders destruction of all icons, beginning the First Iconoclastic Period.

731 Bede completes Ecclesiastical History of the English People.

732 Muslim invasion of Europe stopped by Franks at Battle of Tours, establishing a balance of power between Western Europe, Islam and the Byzantine Empire.

733 Byzantine Emperor Leo the Isaurian withdraws the Balkans, Sicily and Calabria from the jurisdiction of the Pope in response to Pope Gregory III of Rome's support of a revolt in Italy against iconoclasm.

734 Egbert becomes bishop of York, founding a library and making the city a renowned centre of learning.

735 Death of Bede; See of York achieves archepiscopal status.

739 Emperor Leo III (717-41) publishes his Ecloga , designed to introduce Christian principle into law; death of Willibrord.

742 After a forty-year vacancy, Stephen IV becomes Orthodox Patriarch of Antioch, at the suggestion of Umayyad caliph Hisham ibn Abd al-Malik.

747 Witenagamot of England again forbids appeals to the Roman Pope; Council of Clovesho I adopts Roman calendar, observance of the feasts of Gregory the Great and Augustine of Canterbury, and adopts the Rogation Days.

749 Death of John of Damascus.

750 Donation of Constantine accepted as a legitimate document, used by Pope Stephen II to prove territorial and jurisdictional claims.

751 Lombard king Aistulf captures Ravenna and the Romagna, ending Byzantine Exarchate of Ravenna.

752 Death of Pope Zacharias of Rome.

754 Iconoclastic Council held in Constantinople under the authority of Emperor Constantine V Copronymus, condemning icons and declaring itself to be the Seventh Ecumenical Council; Constantine begins dissolution of monasteries.

754 Death of Boniface.

756 Donation of Pepin cedes lands including Ravenna that became basis of Papal States.

768 Wales adopts Orthodox Paschalion and other decrees of the Synod of Whitby at teaching of Elfoddw of Gwynedd.

769 Pope Stephen III of Rome holds a council changing papal election procedure and confirming veneration of icons.

772 Charlemagne starts fighting Saxons and Frisians; Saxony is subdued and converted to Christianity.

781 King Charlemagne of the Franks summons Alcuin of York to head palace school at Aachen (Aix-la-Chapelle) to inspire revival of education in Europe.

785 Synod of Cealchythe erects the Archbishopric of Lichfield.

787 Council of Nicea (Seventh Ecumenical), convened by Empress Irene and her infant son Constantine VI, presided over by Patriarch Tarasius of Constantinople, and attended by 350 Orthodox bishops, and 17 iconoclastic bishops who repent and are received back into Orthodoxy by the council itself. It annuls the decisions of the Mock Council of 754 and condemns Iconoclasm, while restoring the veneration of the sacred icons.

787 Two councils held in England, one in the north at Pincanhale, and the other in the south at Chelsea, reaffirming the faith of the first Six Ecumenical Councils (the decrees of the Seventh having not yet been received), and establishing a third archbishopric at Lichfield.

792 Synod of Regensburg condemned Adoptionism.

793 Sack of Lindisfarne Priory, beginning Viking attacks on England.

794 Charlemagne convenes council in Frankfurt-in-Main, rejecting decrees of Seventh Ecumenical Council and inserting Filioque into Nicene-Constantinopolitan Creed.

800 Charlemagne crowned as Holy Roman Emperor by Leo III of Rome on Christmas day, marking the break of Frankish civilization away from the Orthodox Christian Roman Empire; Book of Kells produced in Ireland.

800 Ambassadors of Caliph Harunu al-Rashid give keys to the Holy Sepulchre to Charlemagne, acknowledging some Frankish control over the interests of Christians in Jerusalem ; establishment of the Western Rite Monastery of Saint Mary in Jerusalem.

801 Controversy in Jerusalem over Frankish pilgrims using Filioque.

803 Council of Clovesho II abolishes archbishopric of Lichfield, restoring the pattern of the two metropolitan archbishoprics (Canterbury and York) which had prevailed before 787, and requires the use of the Western Rite amongst the English speaking peoples.

810 Pope Leo III bans use of Filioque.

814 Conflict between Emperor Leo V and Patr. Nicephorus over iconoclasm; Leo deposes Nicephorus, Nicephorus excommunicates Leo.

826 Ansgar arrives in Denmark and begins preaching; King Harald Klak of Denmark converts to Christianity.

828 Death of Patr. Nicephorus I of Constantinople.

829-842 Icon of the Panagia Portaitissa appears on Mount Athos near Iviron Monastery.

842-843 Council of Constantinople ("Triumph of Orthodoxy"), convened by Roman Empress Theodora, presided over by Patriarch Methodius of Constantinople, and attended by several Orthodox hierarchs, annuls the Iconoclastic Council of 815 and restores the veneration of the holy icons. The iconoclasts and all other heretics are anathematized.

836 Death of Theodore the Studite.

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