When and where
451 in Chalcedon (ancient seaport of Bithynia on the sea
Crisis or controversy
Monophysites were teaching that Christ had a single divine
nature and no human nature.
Convened: Marcianus, Emperor;
Ratified: Leo I, Pope.
Decrees and resolutions
Declared that Christ had two distinct natures and was both true
God and true man;
Promulgated canons of church discipline.