It seemed like a massive intelligence failure on the part of those in power. Everybody in Leinster House knew there was going to be a special debate on the weekend riots.
But soon after the event began last night, Michael McDowell found himself isolated on the Government benches and hopelessly outnumbered by the Opposition.
Many of the protesters across the floor had prepared for the occasion, arriving armed with scripts. The contribution of others was clearly spontaneous. Combined, they numbered about 30 at the height of the debate, while the Minister - by then with only Fianna Fáil's Michael Mulcahy for company - faced them like a thin blue line. Well, a blue line anyway.
Pat Rabbitte noted the particular absence of Mr McDowell's predecessor, John O'Donoghue, who in opposition had "made a career" of holding the justice minister to account over every trifle.
"Now we have mayhem on the streets of the capital," the Labour leader said, and Mr O'Donoghue, along with every other Government TD bar the Minister and one backbencher, had gone missing.
Luckily Mr McDowell was able to fill the vacuum, and his heroic restraint in the face of considerable provocation ensured that the debate took place without serious injury or loss of face for the Government's cause.
The biggest threat came during an exchange with Fine Gael's Jim O'Keeffe.
In a calculated gamble, the Minister had deployed his lawyer's Latin to defuse the protests, quoting Seneca: "Si vis pacem, par bellum" ("If you want peace, prepare for war").
When Mr O'Keeffe promptly retaliated with Cicero - "Salus Populi Suprema Lex" ("The goodwill of the people is the first law"), innocent bystanders in the press gallery feared the situation would escalate. Sanity prevailed, mercifully, and the rest of the debate was conducted in English.
The Minister's main defence was that gardaí had all the resources they deemed necessary on Saturday, including everything from the dog unit to air support - at least until the Garda helicopter broke down.
Part of the Opposition's argument was that the dog unit obviously didn't have an intelligence wing, since their friends in the street could have told them there was going to be trouble.
As Enda Kenny reminded the House, the Taoiseach himself had heard the rumours, or so he seemed to claim on Saturday evening.
None of this worried the Minister, however. Mr McDowell doesn't need an air support unit, being able to look down on the Opposition from wherever he finds himself. And having made clear that he had "no hand, act, or part" in planning for the parade, he defended the Garda's low-key approach, even if it had left them at the mercy of a "drunken rabble".
But he also warned that there would be consequences for handling future parades. "Other events" (ie the 1916 commemoration) were coming, he said, and gardaí "would not be able to ignore" the lessons learned.
His words had an ominous ring, and perhaps helped explain why so many Government backbenchers had already dispersed peacefully.