Arthur Griffith in the context of "Sinn Féin"

The 1921 Anglo-Irish Treaty (Irish: An Conradh Angla-Éireannach), commonly known in Ireland as The Treaty and officially the Articles of Agreement for a Treaty Between Great Britain and Ireland, was an agreement between the government of the United Kingdom of Great Britain and Ireland and the government of the Irish Republic that concluded the Irish War of Independence. It provided for the establishment of the Irish Free State within a year as a self-governing dominion within the "community of nations known as the British Empire", a status "the same as that of the Dominion of Canada". It also provided Northern Ireland, which had been created by the Government of Ireland Act 1920, an option to opt out of the Irish Free State (Article 12), which was exercised by the Parliament of Northern Ireland.

The agreement was signed in London on 6 December 1921, by representatives of the British government (which included Prime Minister David Lloyd George, who was head of the British delegates, and Winston Churchill, who was Secretary of State for the Colonies) and by representatives of the government of the Irish Republic (which included Michael Collins, who was Secretary of State for Finance, and Arthur Griffith, who was Secretary of State for Foreign Affairs). The Irish representatives had plenipotentiary status (negotiators empowered to sign a treaty without reference back to their superiors) acting on behalf of the Irish Republic, though the British government declined to recognise that status. As required by its terms, the agreement was approved by "a meeting" of the members elected to sit in the House of Commons of Southern Ireland and [separately] by the British Parliament. In reality, Dáil Éireann (the legislative assembly for the de facto Irish Republic) first debated then approved the treaty; members then went ahead with the "meeting". Though the treaty was narrowly approved, the split led to the Irish Civil War, which was won by the pro-treaty side.

There were two governments of the 2nd Dáil, which were ministries of Dáil Éireann, the assembly of Dáil Éireann that was the legislature of the Irish Republic, a unilaterally declared state which lasted from 1919 to 1922. The Second Dáil was elected at the 1921 Irish elections on 24 May 1921. The 3rd ministry (26 August 1921 – 9 January 1922) was led by Éamon de Valera as president and lasted 136 days. De Valera resigned as president after the Dáil voted to accept the Anglo-Irish Treaty. The 4th ministry (10 January – 9 September 1922) was led by Arthur Griffith as president. Griffith died in office on 12 August 1922, but a new Dáil ministry was not formed until 9 September 1922. Griffith served 214 days as president, with a further 28 days between his death and the appointment of W. T. Cosgrave as his successor by the Dáil.

The provisional government of Ireland, established under the terms of the Treaty, overlapped with the later period of ministries of Dáil Éireann. The 1st provisional government was led by Michael Collins as Chairman of the Provisional Government from 16 January 1922 until his death on 22 August 1922. On 25 August 1922, W. T. Cosgrave was appointed as his successor, with the other members of the new provisional government appointed on 30 September. The 1st provisional government lasted 218 days from the appointment of Collins until his death, with three days elapsing until the appointment of Cosgrave as his successor.

Dáil Éireann (English: Assembly of Ireland), also called the Revolutionary Dáil, was the revolutionary, unicameral parliament of the Irish Republic from 1919 to 1922. The Dáil was first formed on 21 January 1919 in Dublin by 69 Sinn Féin MPs elected in the 1918 United Kingdom general election, who had won 73 seats of the 105 seats in Ireland, with four party candidates (Arthur Griffith, Éamon de Valera, Eoin MacNeill and Liam Mellows) elected for two constituencies. Their manifesto refused to recognise the British parliament at Westminster and instead established an independent legislature in Dublin. The convention of the First Dáil coincided with the beginning of the War of Independence.

The First Dáil was replaced by the Second Dáil in 1921. Both of these Dála existed under the proclaimed Irish Republic; it was the Second Dáil which narrowly ratified the Anglo-Irish Treaty. The status of the Third Dáil of 1922–1923 was different as it was also recognised by the British. It was elected under the terms of the 1921 Anglo-Irish Treaty as a provisional parliament to pave the way for the creation of an independent Irish state. With the establishment of the Irish Free State in 1922, a new parliament called the Oireachtas was established, of which Dáil Éireann became the lower house.

Dual monarchy occurs when two separate kingdoms are ruled by the same monarch, follow the same foreign policy, exist in a customs union with each other, and have a combined military but are otherwise self-governing. The term is typically used to refer to Austria-Hungary, a dual monarchy that existed from 1867 to 1918 that spanned across parts of Central and Southern Europe, but applies to other dual monarchies such as the Kingdom of Nejd and Hejaz. Dual monarchy is an uncommon form of government, and has been practiced few times in history, although many of the world's most powerful countries have been or are dual monarchies.

In the 1870s, using the Dual Monarchy of Austria-Hungary as a model, the Prince of Wales (later King Edward VII) and William Ewart Gladstone proposed that Ireland and Great Britain form a dual monarchy. Their efforts were unsuccessful, but the idea was later used in 1904 by Arthur Griffith in his seminal work, The Resurrection of Hungary. Griffith noted how in 1867 Hungary went from being part of the Austrian Empire to a separate co-equal kingdom in Austria-Hungary. Though not a monarchist himself, Griffith advocated such an approach for the Anglo-Irish relationship. The idea was not embraced by other Irish political leaders, and Ireland eventually fought a war of independence (1919–1921) to secede from the United Kingdom of Great Britain and Ireland.

The ministry of Dáil Éireann (Irish: Aireacht Dáil Éireann) was the cabinet of the 1919–1922 Irish Republic during the Irish War of Independence. The ministry was originally established by the Dáil Constitution adopted by the First Dáil on 21 January 1919, after it issued the Declaration of Independence. This constitution provided for a cabinet consisting of a head of government, known as the Príomh Aire or President of Dáil Éireann, and four other ministers. The Irish Republic modelled itself on the parliamentary system of government and so its cabinet was appointed by and answerable to the Dáil. Under the constitution the President was elected by the Dáil, while the remaining ministers were nominated by the President and then ratified by the Dáil. The Dáil could dismiss both the cabinet as a whole and individual ministers by passing a resolution. Ministers could also be dismissed by the President.

A number of changes were made to the cabinet system after its adoption in January 1919. The number of ministers was increased in April 1919. As established in 1919, the Irish Republic had no explicit head of state; in 1921 the head of the ministry was renamed as President of the Republic. For a brief period the members of this president's cabinet became known as "secretaries of state" rather than ministers. When the Fourth ministry assumed office in 1922 after the approval of the Anglo-Irish Treaty, with Arthur Griffith as its head, cabinet members were once again described as ministers and Griffith adopted the title of President of Dáil Éireann.

The Chairman of the Provisional Government of the Irish Free State was a transitional post established in January 1922, lasting until the creation of the Irish Free State in December 1922.

The Anglo-Irish Treaty of December 1921 was passed by the Irish Republic's Dáil Éireann. The British government also required it to be passed by the House of Commons of Southern Ireland, and for a legal government to be established. Michael Collins became Chairman of the Provisional Government (i.e. prime minister). He also remained Minister for Finance of Arthur Griffith's republican administration.

Cumann na nGaedheal (Irish: [ˈkʊmˠən̪ˠ n̪ˠə ˈŋeːl̪ˠ], lit. 'Society of the Gaels'), was a political organisation founded in 1900 by Arthur Griffith and William Rooney. Griffith had written an article in the United Irishman newspaper in March 1900, calling for the creation of an association to bring together the disparate nationalist groups of the time, and the result was the formation of Cumann na nGaedheal in September of that year.

In October 1900 Inghinidhe na hÉireann decided to affiliate themselves with the party and as a result were awarded representation on the governing council of the party.

The United Irishman was an Irish nationalist newspaper co-founded by Arthur Griffith and William Rooney. It was first published on 4 March 1899 and ran from 1899 to 1906. Contributors included Oliver St. John Gogarty, Pádraig Pearse, Maud Gonne and Roger Casement. The writer James Joyce is quoted as saying that the United Irishman was "the only newspaper of pretensions in Ireland". In 1906 the United Irishman collapsed under a libel suit and was refounded as Sinn Féin, which ran until 1914 when it was suppressed by the British government.