HistoryData
war1921

Anglo-Irish Treaty — 1921 agreement which ended the Irish War of Independence

December 6, 1921

The Anglo-Irish Treaty of 1921 ended the Irish War of Independence and established the Irish Free State as a self-governing dominion within the British Empire.

Quick Facts

Year
1921
Category
war

Key Facts

Date Signed
6 December 1921
Irish Free State Established
6 December 1922
Status Granted
Dominion, equivalent to Canada
Northern Ireland Opt-Out
Exercised under Article 12
Outcome of Treaty Debate
Narrowly approved by Dáil Éireann
Aftermath
Split led to Irish Civil War, won by pro-treaty side

By the Numbers

6
Date Signed
6
Irish Free State Established
12
Northern Ireland Opt-Out

Location

Map of London, United KingdomMap of London, United KingdomLondon, United Kingdom

Cause → Event → Consequence

Cause

The Irish War of Independence, fought between Irish republican forces and British authorities from 1919 to 1921, created pressure for a negotiated settlement. Both sides agreed to a ceasefire, and plenipotentiary delegates from the Irish Republic traveled to London to negotiate terms with the British government led by Prime Minister David Lloyd George.

Event

On 6 December 1921, representatives of the British government and the Irish Republic signed the Articles of Agreement for a Treaty Between Great Britain and Ireland in London. The agreement provided for the creation of the Irish Free State as a self-governing dominion within the British Empire, with Northern Ireland retaining the right to opt out, which its Parliament exercised.

Consequence

The treaty was narrowly approved by Dáil Éireann, but it deeply divided Irish nationalist opinion over dominion status and the oath of allegiance, triggering the Irish Civil War. The pro-treaty side prevailed, and the Irish Free State came into legal existence on 6 December 1922 when its constitution was enacted by royal proclamation.

Belligerents & Mobilization Analysis

Side A

1 belligerent

United Kingdom of Great Britain and Ireland
Key Commanders

David Lloyd George, Winston Churchill.

Side B

1 belligerent

Irish Republic
Key Commanders

Michael Collins, Arthur Griffith.

Outcome
Agreement ending the Irish War of Independence; establishment of the Irish Free State as a British dominion

Timeline Context

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