First Ecumenical Council
Place: Nicea 1
Date: 325
Purpose: Formulated the First Part of the Creed, defining the divinity of the Son of God
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/fourth-century/the-first-ecumenical-council
Second Ecumenical Council
Place: Constantinople I
Date: 381
Purpose: Formulated the Second Part of the Creed, defining the divinity of the Holy Spirit
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/fourth-century/the-second-ecumenical-council
Third Ecumenical Council
Place: Ephesus
Date: 431
Purpose: Defined Christ as the Incarnate Word of God and Mary as Theotokos
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/fifth-century/third-ecumenical-council
Fourth Ecumenical Council
Place: Chalcedon
Date: 451
Purpose: Defined Christ as Perfect God and Perfect Man in One Person
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/fifth-century/the-fourth-ecumenical-council
Fifth Ecumenical Council
Place: Constantinople II
Date: 553
Purpose: Reconfirmed the Doctrines of the Trinity and of Christ
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/sixth-century/the-fifth-ecumenical-council
Sixth Ecumenical Council
Place: Constantinople III
Date: 680
Purpose: Affirmed the True Humanity of Jesus by insisting upon the reality of His human will and action
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/seventh-century/the-sixth-ecumenical-council
Seventh Ecumenical Council
Place: Nicea II
Date: 787
Purpose: Affirmed the propriety of icons as genuine expressions of the Christian Faith
Learn more: https://www.oca.org/orthodoxy/the-orthodox-faith/church-history/eighth-century/iconoclasm
Notes:
Source of above information: https://www.oca.org/orthodoxy/the-orthodox-faith/doctrine-scripture/sources-of-christian-doctrine/the-councils
See also: https://orthodoxwiki.org/Ecumenical_Councils
Orthodoxy of the Heart 