However, the execution of 15 of the leaders of the rising started to change the mood in Ireland. Support began to ebb away from the constitutional nationalist party towards Sinn Fein, partly because nationalist leader John Redmond was willing to consider the exclusion of part of Ulster from the area promised Home Rule. Threats by the British Government to extend conscription to Ireland also built support for Sinn Fein.

The transformation of the political situation was confirmed in the 1918 elections when Sinn Fein won 73 seats compared to the Home Rule Nationalist Party's six seats. Sinn Fein refused to go to Westminster and instead set up the Dail Eireann as the parliament of the Irish Republic.

Michael Collins was now a leading Sinn Fein member and became a minister in the Dail Eireann executive. Collins' main role was as an organiser for the semi-military Volunteers, which, as the army of the Dail Eireann, became the Irish Republican Army.

The confrontation between the Dail Eireann and Britain developed into the Anglo-Irish war in 1919. Michael Collins was the brains behind the IRA's guerrilla war. Collins' role as military organiser was important, but the IRA's ability to maintain the campaign depended on the information, hiding places, silence and cover provided by a supportive and sympathetic population. Britain's agreement to negotiate was a victory for Collins' tactics but it was also a victory for the mass defiance of the population.

The negotiations led to a treaty which did not make Ireland a Republic and led to partition. The treaty resulted in civil war. Why did Collins agree to it?

The 1921 treaty proposed an 'Irish Free State' within the British Empire. Collins saw this settlement as far from ideal but as a stepping stone to a Republic. He saw that the Irish people would not countenance the continuation of a bloody war over a form of words. The 'Irish Free State' did become a stepping stone to the Irish Republic, formed in 1949.

The opposition to the Treaty inside the Dail, led by Eamon de Valera, did not insist on a Republic as the only acceptable solution. De Valera in fact advocated an "external association" relationship between the Empire and an independent Ireland. De Valera's opposition "Document No. 2" did not mention the word "Republic".

The real tragedy of the Treaty was how it led to partition. Collins and the other negotiators got an agreement that if Northern Ireland continued to exclude itself from the Irish Free State a Boundary Commission would be created to look at the border. Sinn Fein were led to understand that the Boundary Commission would reduce Northern Ireland to four counties. They believed this would make Northern Ireland unviable and inevitably lead to a united Ireland.

Most of the anti-Treaty side agreed with Collins' scenario on the border. De Valera's "Document No.2" accepted the provisions of the Treaty on Ulster. It has been estimated that of 338 pages of debate printed in the Dail report only nine pages are devoted to the question of partition.

The Dail voted to endorse the Treaty. The divisions developed into a bitter civil war. Collins and the pro-Treaty forces won the civil war primarily because the anti-Treaty side had little support among the vast majority of the population.

The Irish labour movement called for an end to the civil war: "To the workers, again, we say: Unite and stand fast! Do not allow yourselves to be drawn into opposing camps". James Larkin, the trade union leader and revolutionary socialist, urged the anti-Treaty IRA to call off the civil war.

Both sides incurred losses at the hands of former comrades. Michael Collins was one of the casualties, killed in an ambush. Soon after his death the anti-Treaty IRA called off the civil war and stated "other means must be sought to safeguard the nation's right".

The civil war itself had not been fought over partition. In fact, it deflected attention from the issue of Ulster. The strategy endorsed by both sides in the war - to rely on the decisions of the Boundary Commission - was shown to be fundamentally flawed when the six county border was reinforced and Northern Ireland was born. This was the real tragedy of the conflict.