Instead, the Anglo-Irish Treaty of 1921, which ended the war in Ireland, allowed the self-governing Irish Free State to be created.
As part of the treaty, Northern Ireland was entitled to opt out of the new Irish Free State, which it did.
Meanwhile the institutions of Southern Ireland generally failed to function or take root as the large majority of Irish Members of Parliament gave their allegiance to Dáil Éireann as part of the Irish War of Independence.
That war ultimately led to the Anglo-Irish Treaty which envisaged the establishment of an independent Dominion, the Irish Free State, provisionally for the entire island of Ireland.
The men pledged to defend their "equal citizenship" within the United Kingdom and that they would not recognize any Parliament forced upon them while the women pledged to support the men.
What Protestants feared that a free Ireland would be dominated by Catholics at their cost.
In 1919, the Irish War of Independence officially began.
The Government of Ireland Act was enacted in 1920, and the island was partitioned into Southern and Northern Ireland the following year, but Home Rule never came into effect in the South.
However, after World War I and the Easter Rising Britain needed to rid itself of what many called the "Irish problem" (constant rebellion and the cost of governing a country that did not want to be ruled).
Finally, a Government of Ireland Act was poised to become law.