Two things happened last night.
Firstly, Britain's place in the world changed. Some will think that is for the better. Britain's role as a world policeman has effectively ended.
Others - and former Lib Dem leader Lord Ashdown has expressed this view this morning - think that Britain is a diminished country that showed it no longer cares about human suffering in other parts of the world.
But as David Cameron acknowledged after his humiliating defeat, the British people spoke through their elected representatives and decided that, this time at least, the UK will not take part in military strikes on Syria if and when they happen.
Ironically, although for entirely different reasons, Britain is now on the same side as Russia in this debate.
And of the five permanent members of the United Nations Security Council, three will not endorse military action on Syria.
That won't change the result - as any one of the five holds a veto - but a diplomatic attempt for a UN resolution is now a route that has been closed off.
The second thing that happened last night was that Mr Cameron spectacularly misread his own party.
Before the summer break, around 80 MPs had already opposed government thinking, which was inching towards arming the Syrian rebels. There was no sign that many of them had changed their minds during the recess.
On Wednesday, one Tory MP I spoke to predicted around 50 members would not back the government motion on Syria. As it happened around 30 rebelled - a smaller number because the Tories did not want to hand Ed Miliband a victory. But it was big enough to hang a large question mark over David Cameron's authority.
The Government maintains the shadow of Iraq was hanging over this debate and yesterday's motion in the Commons. But that didn't stop MPs backing the Prime Minister over action in Libya.
The truth is Mr Cameron leads a party of independently-minded MPs - less willing to follow him blindly into battle. And less willing to support legislation they disagree with too.
Once members have a taste for rebellion, it's hard to make them stop. Tory MPs are less ideologically connected to this government because it's a coaltion. But many of them come from a new generation of politicians.
For example, Dr Sarah Wollaston - the Conservative member for Totnes - was not a party member before the 2010 election campaign. She was elected candidate in a primary. She therefore considers herself firstly a representative of her constituents, and secondly an MP there to support her leader. She rebelled last night and called it "Parliament at its best."
But in the same way as they feel able to act independently, last night's defeat does not mean the Tories will be looking for a new leader.
Mr Cameron's stock had risen in recent weeks. Some of those who voted against him last night told me they still want him to lead the party. One rebel said to me: "If there was a vote of confidence tomorrow he'd win it."
So down, yes. But not out. At least not with his party.
But David Cameron is now out of a club on the world stage. A club of which Britain has been a member for many, many years.
It will make for a fascinating G20 summit in Russia next week. In St Petersburg those leaders who support strike action (Obama) will sit next to those who oppose it (Putin) and those who wanted to support it but no longer can (Cameron).
One vote in the House of Commons. Big changes on the world stage.