A coalition of Labour, the SNP and nearly 40 Conservative rebels handed Prime Minister David Cameron a one-two punch late last night when they voted down the government's amendment to the EU referendum bill and backed the opposition's proposal, instead.
But what actually happened? Was it as "humiliating" as some papers are saying? And what does it mean for the EU referendum and Cameron's leadership?
Just 285 MPs backed the government’s amendment to the EU referendum bill, while 312 MPs voted against it – even after a last-minute retreat by ministers.
The government had proposed a form of “purdah” – a pre-election campaign period – that critics had dismissed as being “watered-down”.
Early last night, in an effort to curry favour with the Tory eurosceptics on the backbench, the government scrapped a separate amendment which would have allowed a so-called “snap” referendum in as few as four weeks.
But the give-away was not enough to keep the eurosceptics sweet. Not only did they "rebel" against the government, they also swiftly backed Labour's more extensive purdah proposals instead.
Was it humiliating?
After the votes were counted, Labour’s shadow foreign secretary Hilary Benn said: “This is a humiliating defeat for David Cameron, with members from all sides of the House supporting Labour’s approach to purdah, which ensures fairness in the conduct of the referendum campaign while permitting normal government business to take place.”
Should Cameron be embarrassed?
It was widely reported that Cameron spent much of yesterday morning wooing eurosceptics in order to win their loyalty. Yet the effort - coupled with the retreat on the snap referendum late last night and many U-turns in recent weeks relating to the timing and wording of referendum intended to satisfy eurosceptic critics - clearly did not work. If anything, it now appears as though the backbenchers, rather than Number 10, are steering the referendum boat.
What happens next?
The EU referendum bill has not received the final sign-off in parliament - it faces further scrutiny in the House of Lords - but eurosceptics insist they are happy with last night's outcome and ready to work constructively with the government.
Yet eurosceptics say last night's Commons chaos was just the beginning of a long road of rowing over the EU referendum.
Even after the bill is done and dusted, there will be the in/out vote itself to worry about. And while the government is expected to campaign to stay "in", leading eurosceptic Bernard Jenkin told Radio 4 this morning that "more than half" of the Tory backbench would push for "out".