The Irish Volunteer Force (IVF) was a paramilitary body publicly launched in Dublin on 25th November 1913. It emerged in response to an article, ‘The North Began’ written by Eoin MacNeill in the Gaelic League paper ‘An Claidheamh Soluis’. He had called on Irish nationalists to form a force to reinforce their demand for home rule, just as Ulster Unionists had established the Ulster Volunteer Force in 1913 to more effectively resist it. Strong Irish Republican Brotherhood involvement in the foundation of the IVF made Redmond, the moderate nationalist leader, reluctant to give it support. But after he was permitted to nominate half the seats on its organising committee (June 1914) he gave his approval. Its membership had reached 160,000 by mid-1914.
The force split in September 1914, following Redmond’s appeal for its members to join the British Army. His supporters and most of the Volunteers broke away and formed the National Volunteers, of whom 35 – 40,000 in due course enlisted. A militant Irish Volunteer rump remained; it was initially reduced to 2-3,000 members but had risen to 15,000 by 1916. Against the will of MacNeill, its Chief-of-Staff, the Irish Republican Brotherhood Military Council successfully infiltrated this force, intending to use it in a wartime rising. The 1,600- strong rebel force in Easter week contained 1,300 Volunteers and over 200 from the Irish Citizen Army; this composite garrison was designated by the insurrectionary leaders as ‘the Army of the Irish Republic’.
After the Rising, the IVF was reorganized on a wave of popular support and some of its members began making active preparations for a renewal of military action. The increasingly repressive measures taken by the British government after the Rising drove the movement underground. Acting on their own initiative, from January 1919, local units launched a guerrilla campaign against police and military personnel, so starting the Anglo-Irish war, 1919-21. The volunteer commanders never fully accepted the central authority either of their own GHQ (established in March 1918) or the political control of the Dail government (set up by the Sinn Féin leadership in Dublin in January 1919), though most took an oath of allegiance to the latter in August 1919. By then, the organisation was increasingly known as the Irish Republican Army (IRA).
In total 15,000 volunteers fought in the Anglo-Irish war, with generally 3,000 active at any one time. Their greatest strength lay in the provinces of Connaught and Munster. They were generally aged between 20 and 30, from middle and working class backgrounds and were overwhelmingly catholic. As the conflict progressed the membership became younger, more urban and more working class. The force fought a limited and successful guerrilla war until stalemate was acknowledged by the Truce (July 1921). The IVF split over the terms of the Treaty (December 1921). A minority supported and joined the Free State Army, quickly built up by Collins with British government support (the ‘regulars’); the majority - perhaps 80 per cent - the most experienced men from the south, west and Dublin, organised and fought against the new state (the ‘irregulars’) in the Civil War, 1922-23. Though the ‘regulars’ won, many of their defeated opponents still refused to accept the legitimacy of either the Irish Free State or of Northern Ireland, and they did not hand in their weapons.