MPs have rejected Theresa May's Brexit plans by an emphatic 432 votes to 202 in a historic vote which has thrown the future of her administration and the nature of the UK's EU withdrawal into doubt.
The humiliating rebuff was delivered in the House of Commons just moments after the Prime Minister made a last-ditch appeal for MPs to back the Withdrawal Agreement which she sealed with Brussels in November after almost two years of negotiation.
The 230-vote margin of defeat was by far the worst suffered by any Government in a meaningful division since at least the First World War and in normal circumstances would be enough to force a Prime Minister from office.
But there was little doubt in Westminster that Mrs May would hang on - and was likely to survive a motion of no-confidence tabled by Labour leader Jeremy Corbyn.
Mrs May now has until January 21 to set out a Plan B - expected to involve going back to Brussels to seek further concessions, with the clock ticking on the scheduled date of Brexit in just 73 days' time on March 29 .
In a statement immediately after her drubbing, Mrs May said: "The House has spoken and this Government will listen."
She offered cross-party talks with MPs across the House to determine a way forward.
Attorney General Geoffrey Cox appeared to indicate that the PM will resist pressure to tear up her plan or to seek cross-party consensus on a new approach.
He told MPs that in the event of a Government defeat the agreement would have to return to the Commons later "in much the same form with much the same content".
Labour leader Jeremy Corbyn told the House of Commons that Mrs May's "catastrophic" defeat represented an "absolutely decisive" verdict on her Brexit negotiations and said he has tabled a vote of confidence.
Moments before the crunch vote, Mrs May told MPs: "Parliament gave the people a choice, we set the clock ticking on our departure and tonight we will determine whether we move forward with a Withdrawal Agreement that honours the vote and sets us on course for a better future.
"The responsibility of each and every one of us at this moment is profound, for this is a historic decision that will set the future of our country for generations."
But the Labour leader called on MPs to vote down the agreement, saying: "This deal is bad for our economy, a bad deal for our democracy, and a bad deal for this country."
As MPs voted, noisy crowds of pro- and anti-Brexit protesters in Parliament Square could be heard inside the Palace of Westminster.
MPs had been due to vote first on a series of four amendments chosen by Speaker John Bercow.
But Mr Corbyn, Scottish National Party leader Ian Blackford and Tory backbencher Sir Edward Leigh opted not to move their amendments, leaving only one division.
In that vote, a proposal from Conservative MP John Baron for the UK to take unilateral powers to end controversial "backstop" arrangements was rejected by 600 votes to 24.
Heavily pregnant Labour MP Tulip Siddiq, who postponed her planned Caesarean in order to vote, attended the Commons in a wheelchair.