In August 1914 Ireland was on the brink of civil war. Supported by the Conservative Party led by Bonar Law and unionist MPs led by Edward Carson and James Craig the Ulster Volunteer Force armed with German rifles and bullets threatened armed revolt against the implementation of Home Rule. In support of Home Rule was the Liberal government led by H.H. Asquith with the support of the Irish Parliamentary Party led by John Redmond. The Irish Volunteer Force had nominal support of Sinn Féin- at the time a monarchist party led by Arthur Griffith - and the Irish Republican Brotherhood who sought to steer its membership toward republican separatism. The much smaller Irish Citizen Army led by thd socialist revolutionary James Connolly was armed with guns smuggled into Howth.
The British Army regiments in Ireland were led by Anglo Irish Protestant officers who were sympathetic to unionism while the lower ranks were majority Irish Catholics sympathetic to Redmond and Home Rule. A group of senior officers threatened the British government that they would not move against the UVF if Home Rule was implemented.
In Sarajevo Archduke Ferdinand the heir to Austro Hungarian throne was assassinated and soon the great powers of Europe were at war.
Home Rule was suspended for the duration.The UVF joined the British Army enmasse keeping their officers and units intact and during 4 years of war were decimated. Veterans later joined the RUC and B Specials after partition in 1920.
Redmond led the majority of the NVF to join the British Army but they were led by Anglo Irish officers and were not allowed to keep their old units. A minority refused and a minority of this minority took part in the 1916 Rising led by Patrick Pearse along with James Connolly's Citizen Army. The Irish War of Independence followed the end of the war and the Irish Civil War afterward.
What would have happened if the Archduke had not been assassinated World War I had not interrupted Home Rule and partition never occurred?
The British officers who were under orders to move against the UVF were not threatening to join forces with them but merely to resign. Asquith would have simply accepted to resignations or sacked them and replaced them with obedient men.
The UVF had plans for an armed rising in Belfast. Had they done so there is little doubt that the British Army would have prevailed against them. The leaders would have been executed and many of the rank and file interned.
Sectarian warfare would probably have broken out and to oppose UVF guerrillas who would have adopted the tactics of the Boers creating flying columns the British would have recruited National Volunteers into their ranks as well as the RIC. Shortages of uniforms would have meant these recruits would wear the dark green RIC tunic and tan khaki trousers. Northern Protestants would call their enemies Black and Tans. A young Corkman named Michael Collins would gain notoriety forming a special unit known as the Squad which would assassinate leading Unionists. Raids reprisals assassinations burning and looting would be the features of this brutal struggle.
By 1921 when the conflict ended the British and Irish Nationalists would have prevailed. As a concession to the Irish leadership an Irish Free State would be created ruled from Dublin led by John Redmond with the support of Arthur Griffith. Patrick Pearse Michael Collins Eamon De Valera and others would form a new party called Fianna Fáil demanding a fully independent Irish Republic. In 1932 they would take power and after the Economic War and the creation of the 1937 Constitution would negotiate the return of the treaty ports.
Taoiseach Pearse would declare Ireland neutral during the subsequent First World War 1939-1941. The German Empire led by Wilhelm IIl would conquer France in 1940 make peace with the British led by Lord Halifax and defeat the Russian Empire led by the young sickly Tsar Alexei in December 1941 after capturing Moscow in a lightening campaign.
For Unionists in Ulster and Southern Unionists and Protestants in the Irish Free State which became the Republic of Ireland in 1949 after the collapse of the British Empire life was grim. A triumphalist Catholic regime set out to gerrymander elections and discriminate against Protestants and English speakers as Gaelic became the language of everyday life.
In 1968 inspired by the example and rhetoric of Martin Luther King a young charismatic preacher named Ian Paisley became the leader of the Civil Rights Movement demanding change. As orange men marched they sang "We Shall Overcome". Peaceful marches were met with vicious violence by the Gardaí and Catholic mobs burned Protestant homes businesses and property. Sectarian warfare broke out and the UVF was reformed declaring itself allied with the ANC in South Africa and the PLO in Palestine.
The Irish Defence Forces deployed to Ulster where they would remain on patrol for decades.
The Irish Army Ranger Wing was accused of conducting a shoot to kill policy.
In 1981 the young Taoiseach Gerry Adams refused to back down when members of the UVF starved themselves to death in the Maze prison.
After years of tortuous negotiations the release of prisoners and disarmament and demilitarization on both sides in 1990 Reverend Ian Paisley was released from prison and in 1994 was overwhelmingly elected leader of a devolved Northern Ireland with its seat at Stormont.