October 8, AD 451

Council of Chalcedon

Council of Chalcedon opens and reviews the council of 449

On opening day the bishops had to sit through a reading of their own words from two years earlier — then loudly disown them.

8 October 451, in St Euphemia

The Council of Chalcedon opened on 8 October 451 in the Church of St Euphemia at Chalcedon, across the Bosporus from Constantinople.

Marcian had transferred the council from Nicaea to nearby Chalcedon, which let the imperial government supervise it more tightly.

The first session was not a drafting meeting but an appeal-style review of the Second Council of Ephesus of 449, conducted by reading its extensive minutes aloud.

Their own words read back

Bishops who had taken part in the 449 proceedings heard their own statements supporting Eutyches and condemning Flavian read back to them, and many responded with vocal expressions of contrition.

Dioscorus of Alexandria was moved from his episcopal seat and treated as the principal defendant, while his accuser Eusebius of Dorylaeum and the restored Theodoret of Cyrrhus were heard amid intense factional protest.

Theodoret’s admission to the session provoked competing cries of “orthodox” and “Nestorian” from the assembled bishops.

None of the famous outcomes happened that day

The session set the council’s direction toward reversing the judgments of 449, but 8 October produced neither the Chalcedonian Definition, nor Dioscorus’s formal deposition, nor Jerusalem’s jurisdictional settlement.

Dioscorus was deposed on 13 October after declining three recorded summonses. The Definition of Faith followed on 22 October and was solemnly approved on 25 October, with 38 high state officials recorded; the Antioch–Jerusalem settlement came on 26 October.

The “November 1” in the listing is the probable final session, at which modern editors argue the last appeal over Canon 28 was heard.

Sources

Researched 23 Aug 2026 6 sources not yet audited

How this was checked

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What the sources leave uncertain

The listed title says 'November 1' while the supplied date is 8 October. These are respectively the probable final date and the secure opening date of the council.
The transmitted acts contain inconsistent session numbering and at least one demonstrably incorrect date; modern editors argue that the final appeal over Canon 28 occurred on 1 November.
Ancient and modern attendance totals vary, and a total for the entire council should not automatically be described as the number present at the opening.
Dioscorus's formal deposition was not a simple verdict that he personally taught Eutyches's doctrine. Modern scholarship stresses procedural and disciplinary grounds, especially his failure to answer the council's summonses.