By Justin Webb
BBC News, Orangeburg, South Carolina
There were two winners. The first, easily on the night, with a grace and poise that will cause concern among her adversaries, was Hillary Clinton.
She addressed her most difficult issue - the war in Iraq - head on and without flinching.
Hillary Clinton said she would not shy away from using military force
"I take responsibility for my vote," that allowed the president to go to war in Iraq, she said.
"If I knew then what I know now we would not have gone to war."
But she made it clear at the same time - this message directed at the wider American public - that if America were to be attacked she would not shy from retaliation, "a military response".
She was the only candidate to grasp that this was a crucial (if vacuous) piece of political posturing if the charge that the Democrats are soft is to be repudiated.
The other big winner, for my money, was Senator Joe Biden.
The senator is an odd character in US politics: he is a deeply serious man with a thoughtful but realistic approach to the world.
But at the same time he can come across as a total buffoon, prolix and pompous and self-regarding to an extent that is incommensurate even with the office of president of the United States.
In this debate he was on disciplined form and he made the evening's best (and only) joke.
Asked straight out whether he could avoid the "uncontrollable verbosity" of his past, the language borrowed from others - he once stole a speech from the former British Labour party leader Neil Kinnock - the Senator paused for a second before answering, "yes".
Senator Biden promised to tone down his rhetoric
And he said not a word more.
The questioner had to accept that he had been defeated, and move on to other matters.
I asked Senator Biden afterwards in the "spin room", where the candidates and reporters all gather, what the point was of these debates, so long before the real event of the election.
"People can get to know us," he said simply.
I think he will have endeared himself to some Democrats and his joke will be played over and over again, getting him just the kind of positive momentum you need from these outings.
The other interesting aspect of the debate was the way in which the left wing of the Democrats was represented with gusto and character by Congressman Dennis Kucinich and former Senator Mike Gravel.
Mr Gravel's strong views clashed with what we all perceive to be the average American world view.
Mr Gravel said the front runners actually frightened him, so addicted were they to war and violence, a comment that would describe the attitude of many around the world to the US itself.
Interesting to hear a presidential candidate voicing that fear. It reminds us all that there is another America, which is not always on show.
But at the same time how fascinating that this other America is really not out of step culturally with the nation at large.
On the basic issue of gun control the candidates were all, of course, in favour.
It was the first debate between all eight Democratic candidates
But when asked who actually had had a gun in the home at some stage of their lives both of the "left-wing" candidates raised their hands.
Only Mrs Clinton, Mr Edwards, and Mr Obama had never kept a firearm at home.
I suspect this will thrill Democratic party strategists, many of whom believe that gun issues lost them the 2000 election.
Even after the Virginia Tech massacre, they do not want the issue raised again.
All in all, a fascinating evening for aficionados of America and American politics.
Most Americans will wait many, many more months before even thinking about their choices, but if they want to join in, the fun has begun.
Next week the Republicans begin their debates. I, for one, cannot wait.