Answer: The Council of Chalcedon was held in 451, from October 8th until November 1st, at Chalcedon, a city of Bithynia in Asia Minor. It was at this Ecumenical Council that the Church defines Jesus Christ as being one divine person, subsisting of two complete natures, one fully divine nature, and one fully human nature.

See:
 • James C. Hamilton, Title :Vatican City A Philatelic History Journey - Part 11 Councils, Synods, World Youth Days, Vatican Notes, Volume 68, Issue PHJ, 2020, Pages 44-47
 • Anonymous, The Council Of Chalcedon Vatican Notes Volume 6, Issue 4, January-February 1958, Page: 4




Council of Chalcedon
Scott # 149-153 (1951)