"...security situation that was rapidly unraveling, per the frantic reports from the Royal Irish Constabulary in particular to Dublin Castle and from there, to London.
Thousands of Irishmen had emigrated to the United States, often for part-time work and remittances, in the half-decade before the Great American War broke out, and tens of thousands more - perhaps as many as a hundred thousand - had departed for American shores as volunteers for the front or to work in factories. Though many died, and many would remain after the rolling peace begun at Lima with Chile and concluding with Mount Vernon with the Confederate States, as early as October 1916, when it was clear the war had weeks to go rather than months or years, foreign soldiers were discharged in droves, and as the spring arrived firings and downsizings at American factories cranked up in earnest as war orders plummeted, spiking unemployment and falling on noncitizen workers especially hard.
Accordingly, Ireland was by mid-1917 awash in tens of thousands of veterans of the GAW, men returning to Ireland for work or to their families after many hard years away, broken mentally and physically in a way that their countrymen could not understand and often radicalized in the United States by its republicanism and the potent "Fenian" organizations there that argued vociferously for Irish independence and Gaelic nationalism, oft-embodied by figures such as Irish-American polemicist and emerging politician Eamon de Valera. Senior IRB recruiters and organizers like Michael Collins had gained invaluable experience observing war in the trenches and the guerilla activities of Confederates in occupied territories, as well as the struggles of the American Army to combat them, and he brought this thinking home with him shortly after the St. Patrick's Day Uprisings along with thousands of experienced, armed and radical soldiers.
May and June 1917 were thus two of the bloodiest months of the conflict, as hundreds of RIC constables, officers in particular, were targeted in ambushes and execution-style killings, and the sophistication of the IRB and other, more revolutionary splinter groups was unlike anything commanders had seen previously. Lord Midleton desperately asked for more reinforcements as activities in India were drawn down, and the UVF's activities began escalating again, culminating in a week of brutal violence in early July that finally forced the government's hand.
On July 7th, 1917, a Catholic parish in South Belfast was firebombed by Ulstermen, with four people inside dying; it was later discovered that the next day, during Sunday mass, had been the true target, but the gang carrying out the attack was frightened out of making such a move at the last moment. Belfast erupted again in outrage, with the Twelfth mere days away and the Irish Army dramatically scaling up its patrols in Ulster to prevent further bloodshed, precisely the type of move that had triggered the Curragh Mutiny in the first place. On Tuesday, July 10th, General Henry Wilson was assassinated in London on the steps of his home - suggesting, finally, that the IRB could reach across the Irish Sea if it so wanted. When news of Wilson's death arrived in Ireland, there were small and spontaneous celebrations that were responded to with RIC crackdowns and shootouts between Collins's "fireteams" organized like American death squads that had been active in Kentucky and Tennessee. The tensions culminated with massive riots, bombings, and shootings on the Twelfth, as Irish Volunteers aggressively did their utmost to derail Orange parades.
"Ireland Burns, Cecil Fiddles," Chamberlain roared in the Commons that following day, but the worst provocation that finally tipped the scales would happen the next day. The Lord Clarence and his wife, as they were driving through Dublin accompanied by their bodyguards, became stuck on Wicklow Street due to a tipped-over dairy carriage blocking their path to College Green to address Irish veterans returned from India. As they were trying to get unstuck, several masked men emerged and opened fire on their car, which thankfully was not uncovered. The Lord Clarence suffered a shattered collarbone as a bullet missed his throat by mere inches and a punctured lung, while the Lady Clarence [1] was wounded in her left shoulder. One of their four bodyguards was killed, but three of the assassins were gunned down in response and the other two subdued by constables and onlookers. It was an obvious ambush, and a well-planned one; the Lord Lieutenant's route through Dublin to Trinity College that day had not been public knowledge, and the decision to address the veterans had been a last-minute one made only the day before due to the violence of the previous week and tensions across the British Isles after Wilson's assassination.
Lord Clarence would live, but only barely, and his survival was still unknown when news arrived in London to Buckingham Palace and King George found out his elder brother had been shot in Dublin. While at first, Special Branch suggested that the IRB had carried out the attack, it quickly became clear thanks to an anonymous leak within the RIC that ultra-loyalists unassociated with the UVF had plotted the attack, likely with help from within Dublin Castle. Wilson's death was proposed as a possible catalyst to move plans forward to kill the Duke and Duchess of Clarence, and the motive was postulated as being the view that the King's brother was overly sympathetic to Irish nationalism, that his renouncing the throne to marry a Catholic was an insult to Anglican England, and that he had insufficiently crushed the enemies of the Crown in his tenure of as Lord Lieutenant and that his death would pave the way for a "proper" administration at Dublin Castle.
Such sentiments, naturally, misread the temperature in Whitehall dramatically, where support for Cecil's government had been in sharp decline for months if not weeks and the National-New Conservative coalition was more tenuous than ever. The "July Days" concluding with the attempted murder of a member of the Royal Family, three years after Ulster nationalists had tried to usurp constitutional order both at Curragh and with the Ulster Covenant, essentially persuaded King George once and for all that British liberalism and Ulsterism were not compatible, and for the first time, he showed his hand on his Hibernophilia on July 16th, when he called Cecil to him.
Whether Cecil had planned to resign in that meeting or not was unclear, but it was obvious at that point that his government had failed to solve Ireland and had only smashed the Ghadar Mutiny in India by the skin of its teeth. George, usually hesitant to directly involve himself in politics, purportedly requested a proposal from Cecil on how exactly the Irish Question "was to be answered," and Cecil's response was clearly found lacking. Later that day, it was Chamberlain called to Buckingham Palace to ask if he could form a "peace government" with the express intent of solving the Irish matter. Chamberlain answered with a qualified affirmation, but requested that Cecil be given the opportunity to resign himself ahead of a confidence vote rather than be sacked by the King personally; this was done not out of any love for Cecil, whom Chamberlain privately loathed, but rather because Chamberlain, who lacked his father's Jupiterian confidence, was a stickler for parliamentary formalities [2] but also wanted to make sure that George Barnes and the SDLP was onboard - not a certainty.
Chamberlain's gamble was that forming a minority government immediately and then moving to invite the IPP back to Parliament with concessions was the only path out, and that elections would need to be called more or less immediately to sustain his government. Barnes signaled his openness to external support for six months in return for concessions on matters of unemployment payments and social housing, to which Chamberlain readily agreed, and on July 20th O'Brien would wield the knife, voting against the government on a tangentially-related act around levies on dairy, which the Liberals and SDLP joined. Cecil's government was defeated on the so-called "milk tax," and Cecil traveled to Buckingham Palace later that day to resign, well aware that his defeat had been planned for a whole week for entirely unrelated reasons. Chamberlain would form an unstable minority government shortly thereafter, declaring to gathered reporters as he arrived at 10 Downing Street that his Cabinet's "exclusive mandate" would be to end the Irish conflict and "find a workable peace." He was the first son of a Prime Minister to take such office since William Pitt the Younger, and after a decade of anticipation, the Chamberlain family was back in charge, in the midst of a firestorm the People's Joe could never have imagined..."
- Ireland Unfree
[1] Helene of Orleans
[2] Churchill observed of Austen Chamberlain IOTL that he lacked the ruthlessness to ever actually rise to the top