Thursday, March 18, 1999 Published at 17:05 GMT
1921-22: The Irish Free State and civil war
Scene of the worst setback in IRA history
Customs House attack The Dublin brigade of the IRA attacks and sets fire to the Customs House in Dublin in May 1921.
Nearly 120 IRA men surrender in one of the biggest setbacks in the organisation's history.
Dual elections Elections are held on both sides of the new border.
Sinn Fein wins 124 of the 128 seats in the south.
Sir James Craig forms a government in the north.
First Ulster parliament This new body assembles on June 7 1921 and is formally opened 15 days later by King George V, who appeals for peace.
Sinn Fein leader Eamon de Valera begins talks in London with Prime Minister Lloyd George.
Craig refuses to attend.
Anglo-Irish Treaty Formal negotiations begin in October and an agreement is eventually signed on December 6, 1921.
The 26 southern counties will become an independent Irish Free State while the six northern counties will remain part of the UK. The treaty sets up a boundary commission to draw the dividing line according to local wishes.
Treaty approved The Dail Eireann votes 64-57 in January 1922 to accept the treaty after a bitter debate in which those backing the deal are accused of treachery.
Special Powers Act Violence escalates in Northern Ireland in March, with more than 230 people killed and about 1,000 wounded - most of the victims are Catholics. The IRA retaliates by targeting the 'B Specials', the part-time police officers made up mainly of members of the Orange Order.
In April, the Royal Ulster Constabulary is formed and the government enacts the Special Powers Act, allowing special courts to detain suspects without trial and impose jail terms or the death penalty.
Irish Civil War A June general election in the Free State is won by those supporting the Anglo-Irish Treaty.
Soon after, two IRA men in London kill Sir Henry Wilson, a British general and security adviser to the Northern Ireland government. The Free State government acts against those opposed to the Treaty and civil war breaks out in the south.
Among the casualties is Michael Collins, one of the signatories of the Treaty, who is shot dead by anti-Treaty republicans in August 1922.
Electoral changes Proportional representation is abolished in Northern Ireland in September.
At Westminster, Lloyd George is ousted by his Conservative allies who win a November general election under Bonar Law.