After their election victory in 1918, the Sinn Féin leaders declared an independent Irish republic and established a government in Dublin. These actions alone were likely to lead to war with Britain; the Westminster government was at that time willing to offer nationalists only very limited powers of self-government.
The Anglo-Irish war, 21st January 1919–11th July 1921 was initiated by a small number of young, determined Irish Volunteers, known from August 1919 as the Irish Republican Army (IRA). They were convinced that a republic could only be gained by force. Some had been preparing for action since shortly after the Easter Rising. From necessity, they adopted a guerrilla campaign. A conventional war of large-scale open conflict was not feasible, given their lack of men, training and arms. They were organised initially into numerous small, fragmented, fiercely independent units who, acting on their own initiative, launched frequent low-level surprise attacks. They then melted back into the civilian population.
The Proclamation expressed the hopes and plans of the revolutionaries. Its primary purpose was to declare that an independent Irish Republic had been established and that a provisional government had been appointed - i.e., the seven members of the Council - to administer temporarily its affairs. Ireland’s ‘national right to freedom and sovereignty’ was powerfully asserted. Though a tiny minority, the rebels claimed: ‘Ireland through us summons her children to her flag’ and could thus ‘prove itself worthy of [its] august destiny’. This appeal for support sprang from their conviction that they were acting in the country’s best interests.
The volunteers attacked government property, carried out raids for desperately needed weapons and funds and, to disrupt the British administration, assassinated prominent individuals. Their most significant single target was the Royal Irish Constabulary. The force was the eyes and ears of Dublin Castle and had the prime responsibility for maintaining law and order. Its members were vulnerable, increasingly unpopular in Ireland, and the best available source of arms. The civilian population was at first shocked by the IRA`s actions but rapidly came to support them out of patriotic sentiment and because of the repressive nature of the British government’s response.
The Sinn Féin government backed the IRA campaign. Michael Collins, a leading figure in both, played a pivotal, co-ordination role. He provided the volunteers with funds, arms and equipment and appointed their officers. He encouraged them to act – identifying targets, issuing instructions and offering advice. His most critical contribution lay in the provision of intelligence, using as sources his network of informers; it penetrated even Dublin Castle and the police forces. During 1919, his ‘squad’, a group of hand picked agents, eliminated Dublin’s detective constables, the ‘G men’. But given the nature of guerrilla warfare, it was the individual volunteer units and their commanders who held the real initiative.
In the course of the Anglo-Irish War, 15,000 volunteers were actively involved, with around 3,000 in service at any given time – sufficient to wage a potent campaign. From the autumn of 1919, the force had sufficient strength to attempt more spectacular actions. Their main purpose was to provoke Westminster into a brutal and repressive retaliatory response. This then served to guarantee popular support in Ireland for the continuing IRA campaign. It was also exploited by Sinn Féin propaganda relating to police atrocities. As these were broadly confirmed by independent journalists, they contributed to a mounting chorus of criticism in Britain and America of the government’s actions.
The violence in Ireland peaked in late 1920. Collins` most celebrated action of the war occurred on 21st November, ‘Bloody Sunday’. On that day his ‘squad’ gunned down 19 suspected British Army intelligence officers living as civilians in Dublin houses and hotels. The incident illustrated the quality of his informants and the continuing devastating capability of the IRA. It immediately stung the security forces into brutal retaliation; hours later, newly recruited members of the police force fired indiscriminately into the crowd at a football match in Dublin, killing 12 people.
By late 1920, IRA strategy had been modified further. In August, the British Army was given powers to intern persons on suspicion without trial. A consequence of the arrests which followed - 4,500 by August 1921 - was that large numbers of volunteers went ‘on the run’. They became in effect professional revolutionaries, differentiated from their part-time colleagues, and with no prospect of normal life until British rule was ended. In Munster especially, these organised themselves into ‘flying columns’ – mobile units of about 100 men, based in remote camps or safe houses - ideally suited to guerrilla warfare.
Throughout the war, the IRA sustained an effective, calculated and flexible campaign. Nonetheless, by mid-1921 the Sinn Féin leadership favoured negotiations with Britain. They considered then that continued violence would break the volunteers, given their lack of men, arms and funds and the steady build-up of troops in Ireland. Moreover, they doubted the capacity of the Irish people to endure more fighting. Also, they were convinced that there was nothing to be gained by it as they were anticipating a generous political settlement. The British government’s offer of negotiations was not conditional on the handover of arms or formal surrender and suggested a real desire for peace.