The party won a clear majority of largely uncontested seats in the 1918 general election, and formed the first Dáil (legislature) of Ireland in Dublin on 21 January 1919.

After what Churchill characterized as some delay and no reply from de Valera, Lloyd George commented: "Must we not admit that the Celts never were Republicans and have no native word for such an idea?

"[9] Lord Longford gives a different account in Peace by Ordeal: "The only doubt in de Valera's mind, as he explained to Lloyd George, arose from the current dispute among Gaelic purists whether the idea Republic was better conveyed by the broader 'Saorstát' or the more abstract 'Poblacht'.

The Easter Rising was short-lived, largely limited to Dublin and, at the time it occurred, enjoyed little support from the Irish general public.

Arthur Griffith's Sinn Féin organisation, which had favoured the establishment of a form of dual monarchy between Ireland and Britain, had not taken part in the Rising.

This agreement was subject to the condition that if the people chose monarchy, no member of the British royal family would be invited to serve as monarch.

"[12] The decision to establish a republic in 1919, rather than any other form of government, was significant because it amounted to a complete repudiation of all constitutional ties with Great Britain, and set the party against any compromise that might involve initial self-government under the Home Rule Act 1914 or continued membership of the British Empire.

One obstacle to this decision—that the Unionists of the north-east had long indicated that they would never participate in any form of a republic—was left unresolved, the six north-eastern counties remaining part of the United Kingdom under the Government of Ireland Act 1920, and later the Anglo-Irish Treaty.

The Republic's leader was known initially as the Príomh Aire, literally "prime minister" but referred to in the English version of the constitution as "President of the Ministry".

On 26 August 1921, de Valera had the Dáil appoint him to the new post of "President of the Republic", so that he would be regarded as the head of state in the forthcoming Treaty negotiations.

Despite being theoretically under the command of the Dáil's Ministry, in practice individual IRA columns enjoyed a high level of autonomy, subject to H.Q.

The extent to which these functioned fluctuated in different parts of the island, with the success or otherwise of republican institutions depending both on the degree of control of the IRA in the region and on the brutality of the Black and Tans and Auxiliaries, active from June 1920 to July 1921.

The more brutal the 'Tans' the more they alienated the local populace from the Dublin Castle administration and Assize courts and the greater success the republican alternatives had.

Efforts by President de Valera in the United States and by the Republic's "ambassador" at the Versailles Peace Conference, Seán T. O'Kelly, to win international recognition failed.

Despite heavy lobbying from prominent Irish-Americans, President Woodrow Wilson refused to raise the Irish case at the conference as he did not want to antagonise the British.

"[18] The issue of recognition raises the question of how much the new Dáil, particularly de Valera, fully appreciated the developing relationship between the victorious powers following the war.

The obvious problem was that the Irish Republic's Declaration of Independence of January 1919 was hostile to Britain, which was one of the four main powers arranging terms at Versailles.

Because its original contents were not seen as workable, the government under David Lloyd George abandoned plans to amend the Third Home Rule Act enacted in 1914, having called the Irish Convention in 1917–18.

The British cabinet started in September 1919 to work from Walter Long's 1918 proposals, and in December 1920 they enacted the Government of Ireland Act 1920.

While rejecting the right of the British parliament to legislate for Ireland, Sinn Féin took the opportunity of the two general elections in May 1921, one in the north and one in the south, to seek a renewed mandate for the Republic.

The new Northern Ireland parliament in Belfast first sat on 7 June 1921 with a large Ulster Unionist majority and, while it did not formally recognise the Republic, its premier, Sir James Craig, had secretly met with Éamon de Valera in Dublin in May 1921.

On 14 July 1921 Éamon de Valera met David Lloyd George in London for the first time to find some common ground for a settlement.

[21] In August, in preparation for the formalities, de Valera had the Dáil upgrade his status from prime minister to full President of the Republic.

However, the British view was that they were not envoys, and they recognised them only as elected members of parliament representing those Irish people who wanted independence in one form or another.

Michael Collins was designated as Chairman of the Provisional Government, in theory answerable to the House of Commons of Southern Ireland and appointed by the Lord Lieutenant.

However the two administrations were progressively merged until in August, following the deaths of both Griffith and Collins, W. T. Cosgrave assumed both leadership positions simultaneously and so the two most important offices effectively became one, producing a unique constitutional hybrid; a crown-appointed prime minister and a president of a republic.

The Civil War began in June 1922 when both Sinn Féin and the IRA split between those pragmatists, who supported the Treaty, and the hardline republicans who opposed the compromises it contained.

After the Irish electorate voted in a majority of pro-Treaty candidates to the Dáil, Éamon de Valera declared that "the people have no right to do wrong."

Their line of authority included some TDs but also the Army Executive of the IRA which decided in early 1922 that it, and no longer the Dáil, was the only body loyal to the republic.

In March 1926, de Valera, along with most anti-Treaty politicians, founded a new party called Fianna Fáil and ended their boycott of the institutions of the Free State.