"...the most critical gamble in the history of Ireland. Redmond knew, of course, that his health was failing, and that he had at best six months to live, possibly less if he kept up the rigors of his schedule at the Irish Convention. The forces against compromise "coalesce in the dark," he wrote ominously in a private letter to his oft-rival Dillon, "and if we do not seize the hour, they will surely in time overwhelm us."
John Redmond's most important speech of his life was thus given on January 4, 1918, as the Convention reopened. Holding up the signed document from Midleton outlining a substantial concession - that Westminster would devolve the powers of customs and excise to an Irish Parliament on the condition that this proposed Parliament did not levy customs in excess of Westminster's rates against any other member of the British Empire such as Canada or Australia, essentially cementing the soft version of the Federation - he announced his "unqualified support for this compromise" and suggested that the "time for Ireland is today." Key to Midleton's letter had been the note from Chamberlain personally that if "substantial agreement" was found (in other words, if most parties excluding Ulster found this arrangement workable) then Westminster would proceed apace to vote through such an act, though Redmond suspected, correctly, that Chamberlain would have to call an election on the question, as the time of his agreement with Barnes was fast running out and the Parliamentary numbers were too fragile to ram through this very radical Home Rule solution.
It is important to note here just how radical the New Year's Day Agreement, as it came to be known, was in contrast to even Home Rule bills from earlier proposals. The Irish would "evacuate" Westminster entirely, to be represented exclusively by the Irish Assembly, which would have a House of Commons of one hundred and sixty-five Members of the Assembly, and a Senate with sixty-four members elected to rotating ten-year fixed terms divorced from national elections, with each county represented by two members. Further, safeguards would be put in place for provincial and county authority; each county would have a strongly empowered local board in charge of roads and housing, and if a majority of Senators from one of the four provinces voted against an act of the Commons, that was sufficient to delay its passage by a period of a year, in which time it would be reintroduced to the Senate for an up-down vote; this was officially termed the "provincial courtesy" in Redmond's diaries, but it was widely understood to be a provision to mollify Ulster's concerns about being outnumbered and overrun by Southern nationalists, and thus in time came to be known colloquially - and ruefully - as the "Ulster Veto." [1]
What this meant was that, unlike early requests, Ireland would have no House of Lords that protected the almost uniformly Protestant Irish aristocracy with the same means that the British counterpart did; it meant that the highly emotional schools question, on which the Catholic hierarchy had been rigidly opposed to compromise, was punted to a future Irish Assembly to solve (a note which Ulster's representatives were quick to point out), and that on every fiscal question, the Nationalists and the moderate Southern Unionists had won out. Ireland would stay inside the British Empire, with the King as their sovereign and the privilege of the Lord Lieutenant as his viceroy rather than a mere Governor-General, such as in the Dominions; but there was no question that this was the maneuver that went beyond Grattanism and made Ireland a Dominion, rather than a co-Kingdom such as Austria and Hungary (news of frequent and worsening constitutional crises in Hungary throughout 1917 surely had an impact on Redmond's thinking here, even if there is no written evidence for it). [2]
Somehow, after nearly four years of bloodshed and sectarian hate in Ireland, the forces of compromise came together. Carson, splitting from Craig, viewed the protections of the Midleton Agreement as sufficient to protect Ulster interests and quietly supported the deal, confident that there would be no better arrangement for Ulster in the offing. [3] Samuel moved quickly in the afternoon of the 4th to take a preliminary vote on the question, and was pleasantly surprised [4] when it achieved near-unanimity from those present. The Irish Convention had done its job, even if much remained - it had produced a settlement for Ireland, by Irish representatives. The hour of an Irish Dominion governed by the Irish exclusively was nigh.
Of course, there was one critical step remaining - the passage of a Government of Ireland Act under the auspices produced by the Convention, and for that the onus now moved to Westminster and Austen Chamberlain, at exactly the moment when many Ulster Loyalists and Catholic nationalists began to sour on the agreement produced...."
- Ireland Unfree
[1] These provisions are of my own invention
[2] As Dan pointed out, but I was already working on this update and thus was able to weave his thoughts in
[3] This is actually true to OTL - Carson had come around to some level of openness around a compromise by the time of the Irish Convention and turned against it when it was clear Sinn Fein was firm on full and total republicanism and separation. With Sinn Fein just a Grattanist outfit here and Redmond/Devlin in control, and the considerable safeguards for Ulster built into this agreement, he is okay with it.
[4] Here is the key difference - the OTL Convention's chairman, Plunkett, adjourned for two weeks rather than take a vote on the deal on a day when everybody was ready to cut one. This gave Sinn Fein, nationalist bishops, and conservative Ulstermen the chance to start campaigning against it, and Redmond's health got a lot worse, and Devlin blew up the deal and Redmond decided not to break with Devlin. They were so, so close to an actual United Ireland in January of 1918.