Original: The Council of Chalcedon was an ecumenical council of the Christian Church, held from 8 October to 1 November 451 at Chalcedon (a city of Bithynia in Asia Minor).
Simplified: The Council of Chalcedon was an ecumenical council that took place from October 8 to November 1, 451, at Chalcedon (a city of Bithynia in Asia Minor).