MPs have dramatically rejected crashing out of the European Union without a deal at any time and under any circumstances.
In a surprise move, the Commons voted 312 to 308 - a majority of four - in favour of an amendment tabled by Tory former cabinet minister Dame Caroline Spelman.
And the vote was later confirmed by a more emphatic 321 votes to 278 when the Government's motion was put forward as amended.
However, in a second vote less than an hour later, the motion to reject a no-deal Brexit passed 321-278, a majority of 43.
"The House has today provided a clear majority against leaving without a deal," Prime Minister May said.
Mrs May said that MPs will vote tomorrow on an extension to Article 50, which could involve a short delay to implement a deal agreed in the next few days or a longer delay if no agreement is reached.
Labour leader Jeremy Corbyn said that Parliament must now take control of the Brexit process and his party will work across the House of Commons to seek a compromise solution.
Labour MP Maria Eagle said Theresa May has “lost all authority” following the vote.
She whipped it (having said she wouldn’t) voted against it (having said she’d vote for it) and lost big. She then told the House “nothing has changed” She has lost all authority. https://t.co/tXn8vDNaJQ
— Maria Eagle MP (@meaglemp) March 13, 2019
The fallout of the votes has seen its first ministerial casualty. Sarah Newton has resigned as a minister at the Department for Work and Pensions over the Brexit vote, a DWP source said.
After the first vote, European Research Group chairman Jacob Rees-Mogg said the amendment had no legal force.
He told Sky News: “We live under a system of law and a motion passed in Parliament does not override the law.”
Both UK and EU law had March 29 as the leaving date, regardless of the vote, he added.
“This vote is very interesting, and the Government may or may not pay attention to it, but it is not binding, it is not law,” he said.
Commons overwhelmingly rejected an amendment that would have delayed Brexit to May 22, offered a transition phase to the end of 2021 and no backstop commitment.
The vote failed 164-374, a majority of 210.
Earlier
The House of Commons votes tonight on a motion that "declines to approve leaving the European Union without a withdrawal agreement and a framework on the future relationship on 29 March".
If the motion passes, there will be another vote tomorrow to decide whether the UK will delay Article 50.
If the motion fails, the UK leaving the EU without a deal becomes a step closer to being a reality.
'I think it's still alive': Tory MP says May’s Brexit deal could return to the Commons - and win
The Chief Secretary to the Treasury in Westminster has suggested that Theresa May’s Brexit deal could be brought back to the Commons and win majority support, despite twice being rejected by large margins.
“I think it is still alive, I do,” Liz Truss told BBC Radio.
“Ultimately, when you look at the alternatives – which are a customs union, no Brexit or no-deal – Theresa May’s deal is more attractive than those other three options.
“I think that’s the conclusion MPs will ultimately come to.”
Ms Truss said she was “not inclined” to vote for the Government motion in Wednesday’s free vote, telling the BBC: “I’m going to vote to keep no-deal on the table.”