[25][29] Its initial political platform was both conservative and monarchist, advocating for an Anglo-Irish dual monarchy unified with the British Crown (inspired by the Austro-Hungarian Compromise of 1867).

The pro-Treaty and anti-Treaty components (led by Michael Collins and Éamon de Valera respectively) managed to agree on a "Coalition Panel" of Sinn Féin candidates to stand in the 1922 general election.

[37] Pro-Treaty Dáil deputies and other Treaty supporters formed a new party, Cumann na nGaedheal, on 27 April 1923 at a meeting in Dublin, where delegates agreed on a constitution and political programme.

At a special Ard Fheis in March 1926, de Valera proposed that elected members be allowed to take their seats in the Dáil if and when the controversial Oath of Allegiance was removed.

When his motion was defeated, de Valera resigned from Sinn Féin; on 16 May 1926, he founded his own party, Fianna Fáil, which was dedicated to republicanising the Free State from within its political structures.

[44] Fianna Fáil came to power at the 1932 general election (to begin what would be an unbroken 16-year spell in government) and went on to long dominate politics in the independent Irish state.

The emergence of a popular new republican party, led by former IRA members, in Clann na Poblachta, threatened to void any remaining purpose Sinn Féin had left.

Its report angered the already disaffected traditional republican element within the party, notably Seán Mac Stíofáin and Ruairí Ó Brádaigh, who viewed such a policy as treason against the Irish Republic.

[54] A similar motion had been adopted at an IRA convention the previous month, leading to the formation of a Provisional Army Council by Mac Stíofáin and other members opposed to the leadership.

[71] Over the next few years, Adams and those aligned with him would extend their influence throughout the republican movement and slowly marginalise Ó Brádaigh, part of a general trend of power in both Sinn Féin and the IRA shifting north.

[73] The prisoners' protest climaxed with the 1981 hunger strike, during which striker Bobby Sands was elected Member of Parliament for Fermanagh and South Tyrone as an Anti H-Block candidate.

[77] Sinn Féin polled over 100,000 votes in the Westminster elections that year, and Adams won the West Belfast seat that had been held by the Social Democratic and Labour Party (SDLP).

At the 1983 Ard Fheis the constitution was amended to remove the ban on the discussion of abstentionism to allow Sinn Féin to run a candidate in the forthcoming European elections.

[86][87][88] Ó Caoláin's entry to the Dáil marked the beginning of a continuous Sinn Féin presence in the Republic of Ireland's national political bodies.

They nearly reached a deal in November 2004, but the DUP insisted on photographic or video evidence that decommissioning of IRA weapons had been carried out, which was unacceptable to Sinn Féin.

[93] On 2 September 2006, Martin McGuinness publicly stated that Sinn Féin would refuse to participate in a shadow assembly at Stormont, asserting that his party would only take part in negotiations that were aimed at restoring a power-sharing government.

The most well-known opponent was former IRA prisoner Gerry McGeough, who stood in the 2007 Assembly election against Sinn Féin in the constituency of Fermanagh and South Tyrone, as an Independent Republican.

[102] Sinn Féin were opposed to Northern Ireland leaving the European Union together with the rest of the United Kingdom, with Martin McGuinness suggesting a referendum on the reunification of Ireland immediately after the 2016 United Kingdom European Union membership referendum results were announced,[105] a stance later reiterated by McDonald as a way of resolving the border issues raised by Brexit.

This information did not become publicly known until 2022 and the move was criticised in some quarters on the basis that it would be wrong for Sinn Féin to work with dissident republican groups which do not repudiate violence by paramilitaries.

The Irish Republican Army wages an armed campaign... Sinn Féin maintains the propaganda war and is the public and political voice of the movement".

[133] Sinn Féin has argued that the IMC is not independent, and that the inclusion of former Alliance Party leader John Alderdice and a British security head was proof of this.

[145] On 10 March 2005, the House of Commons in London passed without significant opposition a motion, introduced by the British government, to withdraw the allowances of the four Sinn Féin MPs for one year, in response to the Northern Bank Robbery.

[158][159] Some critics inside Sinn Féin have opined that decision-making in the party rests with the officer board and that the Árd Comhairle serves merely to rubberstamp decisions that have already been made.

[206] The party was critical of the supposed need for an EU constitution as proposed in 2002,[207] and urged a "No" vote in the 2008 referendum on the Lisbon Treaty, although Mary Lou McDonald said that there was "no contradiction in being pro-Europe, but anti-treaty".

The party expresses, on one hand, "support for Europe-wide measures that promote and enhance human rights, equality and the all-Ireland agenda", and on the other a "principled opposition" to a European superstate.

[211] Since moving to this "soft Euroscepticism" position, Sinn Féin support a policy of "critical engagement with the EU", and have a "principled opposition" to a European superstate.

By the beginning of 1985, Sinn Féin had won its first representation on local councils, owing to three by-election wins in Omagh (Seamus Kerr, May 1983) and Belfast (Alex Maskey in June 1983 and Sean McKnight in March 1984).

[242] After negotiations with the left-wing Independent TDs Finian McGrath and Maureen O'Sullivan, a Technical Group was formed in the Dáil to give its members more speaking time.

[249][250] Party leader Mary Lou McDonald called the result a "revolution" and announced she would pursue the formation of a government including Sinn Féin.

[260] In the South constituency their candidate, Councillor Toiréasa Ferris, managed to nearly double the number of first preference votes,[260] lying third after the first count, but failed to get enough transfers to win a seat.