The clash between the and of the controversial budget of , produced the which enabled the veto of the Lords to be overturned. Given that the Lords had been the unionists' main guarantee that a home rule act would not be enacted, because of the majority of pro-unionist peers in the House, the Parliament Act made a likely prospect in Ireland. Opponents to Home Rule, from leaders like and to militant unionists in Ireland threatened the use of violence, producing the incident in 1912, when they smuggled thousands of rifles and rounds of ammunition from for the . Randolph Churchill famously told a unionist audience in Ulster that "Ulster will fight, and Ulster will be right".
The prospect of civil war in Ireland was seen by some as likely. In 1914 the , which contained provision for a temporary partition, received the . However its implementation was suspended for the duration of the intervening , which was only expected to last a few weeks but lasted four years. But by the time it concluded, the Act was seen as dead in the water, with public opinion in the majority nationalist community having moved from a demand for home rule to something more substantial, independence. proposed in 1919 a new bill which would divide Ireland into two Home Rule areas, twenty-six counties being ruled from Dublin, six being ruled from Belfast, with a shared appointing both executives and a , which Lloyd-George believed would evolve into an all-island parliament.
Partition of Ireland, partition of Ulster
In United Kingdom law, Ireland was partitioned in 1921 under the terms of the Government of Ireland Act 1920. Six of the nine Ulster counties in the north-east formed Northern Ireland and the remaining three counties joined those of Leinster, Munster and Connacht to form Southern Ireland. Whilst the former came into being, the latter had only a momentary existence to ratify (in United Kingdom law) the Anglo-Irish Treaty that ended the Anglo-Irish War.
Under the Anglo-Irish Treaty, Northern Ireland was provisionally scheduled to be included in the Irish Free State, though it could opt out should the Parliament of Northern Ireland elect so to do.As expected it did so immediately. Once that happened, as provided for, an Irish Boundary Commission came into being, to decide on the territorial boundaries between the Irish Free State and Northern Ireland. Though leaders in Dublin expected a substantial reduction in the territory of Northern Ireland, with nationalist areas like south Armagh, Tyrone and urban territories like Londonderry and Newry moving to the Free State, it appears that the Boundary Commission decided against this. The British and Irish governments agreed to leave the boundaries as they were defined in the 1920 Act. The Council of Ireland provided for in the Treaty, to link Northern Ireland and the Irish Free State, did not come into being
